fig1 shows an embodiment of the present invention in the context of a single reel magnetic tape drive 20 . in particular , fig1 shows the tape drive 20 with a tape cartridge 24 positioned within the tape drive wherein magnetic or other data storage tape 28 is wound around the cartridge hub 32 . however , during operation , the magnetic tape 24 is automatically threaded through the tape drive 20 , over the read / write head 38 ( for reading from and / or writing to the tape ) and subsequently wound on the take up assembly 40 , and more particularly , wound around the take up reel hub 42 . to provide a better appreciation as to the relationship between various components of the present invention and the tape cartridge 24 , reference is made to fig2 wherein a partially exploded view of a tape drive assembly 44 is provided having both the tape drive 20 and the tape cartridge 24 therein . moreover , this figure shows the tape cartridge 24 operably positioned adjacent to the tape drive 20 for reading and / or writing of the tape 28 . note that the tape drive assembly 44 includes a front panel 48 with a door 52 covering an opening for entry and exit of the tape cartridge 24 from the tape drive assembly 44 . thus , the tape drive assembly 44 is designed to accept tape cartridges 24 having a configuration and orientation substantially as shown in fig1 and 2 during operation of the tape drive 20 . referring to the tape cartridge 24 in somewhat more detail , it includes a substantially cylindrical leader or tape pin 56 ( fig1 and 4 ) attached to an end of the tape 28 such that when the tape 28 is fully retracted into the tape cartridge 24 ( and thus wound about the cartridge hub 32 ), the leader or tape pin 56 seats within the pin recess 59 of the tape cartridge . the leader pin 56 has five sections ; they are : ( i ) a central cylindrical body 58 , ( ii ) two pin slots 60 , one at each end of the cylindrical body wherein each pin slot includes a reduced diameter cylindrical slot interior 62 and two opposing sides 64 ; and ( iii ) two cylindrical end pieces 66 , one at each end of the leader pin . the pin recess 59 includes two spaced apart pin stays 65 that are positioned so that the leader pin 56 seats against these stays 65 when resting within the recess 59 . in particular , each end piece 66 seats with an adjacent pin stay 65 so that the pin slots 60 are not occluded by the pin stays 65 and therefore remain fully accessible from the interior of the tape cartridge 24 . that is , the pin stays 65 do not restrict access to the reduced diameter cylindrical slot interiors 62 . returning now to fig1 note that a threader band 80 ( also denoted a leader ) is provided within the tape drive 20 for threading the tape 28 through the tape drive 20 . in particular , the leader 80 is threaded along the leader path 82 which is , in one embodiment , two parallel spaced apart slots 84 provided within a threading frame 88 ( fig1 and 3 ). accordingly , the leader 80 is attached at one end to the take up reel assembly 40 while the other end of the leader has a hook 94 attached thereto for hooking the leader pin 56 for threading the tape 28 through the tape drive along a similar ( but not identical ) path as the leader path 82 taken by the leader 80 . thus , once the pin 56 is secured by the hook 94 , the take up reel assembly 40 rotates thereby winding the leader 80 on the take up reel assembly 40 and consequently threading the magnetic tape through the tape drive 20 . a more detailed illustration of an embodiment of the hook end of the leader 80 is shown in fig5 . in particular , note that the leader 80 has two spaced apart parallel threading bands 98 that are only connected to one another via their attachments at one end to the take up reel assembly 40 , and via the connector , e . g . hook subassembly 94 , at the opposite end of the threading bands . the threading bands 98 are spaced apart a distance appropriate for freely moving in the parallel slots 84 ( fig3 ) in the direction of the leader path 82 . moreover , note that such spacing between the threading bands 98 is greater than the width of the magnetic tape 28 ; e . g ., for a magnetic tape having a width of about 12 . 65 mm , the threading bands 98 may be spaced apart by about 17 mm . each threading band 98 includes a series of equally spaced holes 102 spaced along the end of the threading band 98 adjacent to where the hook subassembly 94 attaches thereto . these holes 102 are for engaging the teeth of a sprocket and thereby assuring that the hook end of the leader 80 moves in a desired manner during the hooking and unhooking of the leader pin 56 ( as will be further described hereinbelow ). additionally , at least one of the threading bands 98 includes sensor holes 106 for allowing light from light - emitting sensors within the tape drive 20 to pass through the threading band for detection by corresponding light - receiving sensor along the leader path 82 as will also be described further hereinbelow . regarding the hook subassembly 94 , included therein are two pin hooks 110 with a stay 114 fixedly attached therebetween . each of the pin hooks 110 has one end attached to a threading band 98 . from this attachment each pin hook 110 extends in a particularly advantageous hook shape for reliably hooking and unhooking the leader pin 56 . in particular , each of the pin hooks 110 is curved for entering into a corresponding one of the pin slots 60 so that the slot interior 62 of the pin slot is captured within the interior of the pin hook in a manner that substantially precludes accidental dislodgement therefrom during threading or unthreading of the magnetic tape from the tape drive 20 . fig6 shows a view of one of the pin hooks 110 thereby illustrating the novel shape of the pin hook . however , in order to more fully appreciate the functional aspects of the pin hook 110 , a brief description of the hooking action is now provided . accordingly , for hooking the slot interiors 62 of the leader pin 56 , each pin hook 110 enters the tape cartridge 24 through the opening 68 wherein each pin hook 110 is adjacent to one of the pin slots 60 . subsequently , the pin hooks 110 are synchronously pivoted clockwise ( in a manner further described hereinbelow ) so that the hook opening 118 of each pin hook 110 rotates into alignment with the adjacent slot interior 62 . thus , as the leader 80 retracts from the tape cartridge 24 , each slot interior 62 enters the adjacent hook opening 118 and subsequently traverses the hook interior along the direction of arrow 122 until the slot interior contacts the closed end 126 of the pin hook . note that the unhooking action is substantially the reverse of the hooking action . that is , the hooked leader pin 56 seats in the pin recess 59 , the hook pins 110 disengage from the slot interiors 62 by entering the tape cartridge 24 , the hook subassembly 94 is rotated counterclockwise so that when it is retracted from the tape cartridge 24 , the pin hooks 110 can retract from the tape cartridge without re - engaging the slot interiors 62 , and additionally , without re - engaging the leader pin 56 . accordingly , given the above hooking and unhooking description , the novel curvature of the pin hooks 110 may now be appreciated . in particular , note that the hook opening 118 is angled from the plane or width of the leader 98 ( fig6 ) at about 30 ° ( more generally , in a range of 10 ° to 45 °), and the hook opening 118 has a width ( at arrow 130 ) that is somewhat wider than the diameter d of the slot interior 76 ( e . g ., the width being about 1 . 7 mm for d being about 1 . 6 mm ). thus , when the hook 94 rotates clockwise and is retracted from the tape cartridge 24 , the pin hooks 110 easily grasp the slot interiors 62 . subsequently , upon further retraction of the hook subassembly 94 out of the tape cartridge 24 , each slot interior 62 slides along the path indicated by the arrow 122 of the hook interior 124 and seats at the closed end 126 of the pin hook . thus , since the pin hook interior width ( e . g ., at the arrows 132 ) is only marginally wider than the diameter d of the slot interior 62 , and since the thickness 134 ( fig5 ) of each pin hook is only marginally smaller than the distance between the parallel sides 64 of a pin slot 60 , each pin hook snugly engages the leader pin 56 such that there is substantially no lateral leader pin movement transverse to a direction it travels along the leader path 82 . moreover , since the pin hook interior is angled relative to the directions ( e . g ., arrows 134 and 138 ) of hook subassembly 94 movement during the tape threading and / or unthreading processes , the leader pin 56 is not susceptible to disengagement from the pin hooks 110 in the directions of arrows 134 and 138 . in particular , when the engaged leader pin and hook subassembly 94 are rapidly slowed down during the threading and / or unthreading process , any potential movement for decoupling the pin 56 and the hook subassembly 94 is substantially precluded since such movement is likely to be in the directions of arrows 134 and 138 and not in the angled direction that the leader pin would have to travel in order to exit from one or both of the pin hooks 110 . thus , the pin 56 and the hook subassembly 94 remain reliably engaged during the threading and unthreading operations of the tape drive 20 . as described hereinabove , during hooking and unhooking of the pin 56 by the hook subassembly 94 , the hook subassembly is rotated clockwise and counterclockwise respectively . the hook pivot assembly 160 ( e . g ., fig1 , 7 , 8 a - 8 e ) performs this task . referring to fig1 and 7 , the hook pivot assembly 160 is pivotable as a unit about pivots 164 ( shown in fig7 as separate components of the tape drive 20 that attach the hook pivot assembly 160 to the remainder of the tape drive 20 ; however , various arrangements of pivots 164 are within the scope of the invention including pivots that are integral with , e . g ., the upper and lower threading tracks 176 a and b described hereinbelow ). the hook pivot assembly 160 is also biased to pivot in a counterclockwise direction by the spring 168 ( fig1 ) wherein the spring attaches at one end to the pivot assembly 160 and the other end to the threading frame 88 . as can be best seen in fig6 the pivot assembly 160 includes an end portion of the leader path 82 which includes the upper and lower threading tracks 176 c and d that provide paths for the threading bands 98 along the leader path 82 through the hook pivot assembly 160 . note that each of the threading tracks 176 a - d has a ledge 180 that functions as a guide for the threading bands 98 . moreover , note that each of the threading tracks 176 a - d is at least partially provided in a corresponding recess 184 that also serves as a threading band guide along the leader path 82 . the hook pivot assembly 160 also includes a motor 188 for driving a plurality of gears that cause the hook pivot assembly 160 to pivot , and also cause the hook 94 subassembly to move into and out of the tape cartridge 24 in the direction of the leader path 82 adjacent to the magnetic tape exit from the tape cartridge 24 . note that there are four gears included in the hook pivot assembly 160 , these being : ( i ) a drive gear 192 which is attached to the shaft 186 of the motor 188 , wherein the drive gear is directly driven by the motor ; ( ii ) a planetary gear 196 which is driven by the drive gear 192 ; ( iii ) a sprocket gear 200 which is intermittently driven by the planetary gear 196 , wherein the sprocket gear , in turn , is attached to and rotates a pair of sprockets 204 ( only one of which is shown in fig7 ) for moving the leader 80 along the leader path 82 ( as will be further described hereinbelow ); and ( iv ) a cam gear 208 which is also intermittently driven by the planetary gear 196 , wherein the cam gear , in turn , is attached to and rotates a cam 212 for pivoting the hook pivot assembly 160 ( as will also be further described hereinbelow ). additionally , note that the planetary gear 196 is attached to the remainder of the hook pivot assembly 160 by an arm 216 ( fig1 , and 9 ) that pivots about the shaft 186 . in particular , the planetary gear 196 is rotatably attached to the end of the arm 216 opposite the arm attachment to the shaft 186 . thus , the arm 216 is able to pivot the planetary gear 196 between at least a first position for engaging the teeth of the sprocket gear 200 , and a second position for engaging the teeth of the cam gear 208 . referring now primarily to fig8 a - 8f , the operation of the pivot assembly 160 during the attaching of the hook 94 to the leader pin 56 is shown . accordingly , in fig8 a , the pivot assembly 160 is in an inactive state , wherein the leader 80 extends along the leader path 82 from the take up reel assembly 40 to the open end 220 of the leader path . moreover , at least one hole 102 of each threading band 98 , nearest the hook 94 , is grasped by the pair of sprockets 204 thereby securely holding each threading band 98 in its corresponding threading track 176 . upon receiving a request for threading a tape through the tape drive 20 , an electronic controller ( not shown ) therein activates the motor 188 to rotate counterclockwise as shown in fig8 b . accordingly , the drive gear 192 causes the planetary gear 196 to rotate clockwise . moreover , substantially concurrently with the activation of the motor 188 , the arm 216 pivots counterclockwise so that the teeth of the planetary gear 196 meshes with the teeth of the sprocket gear 200 . thus , the counterclockwise rotation of the drive gear 192 induces a counterclockwise rotation of the sprockets 204 . moreover , since the spacing of the holes 102 match the spacing between the teeth of each of the sprockets 204 , the sprocket teeth mate with the holes 102 to thereby urge the hook 94 to extend out of the open end 220 of the pivot assembly , and into the tape cartridge 24 as shown in fig8 c . in particular , note that the hook 94 extends further into the tape cartridge 24 than where the pin 56 is seated against the pin stays 64 . additionally , once the motor 188 stops and the hook subassembly 94 is maximally extended into the tape cartridge 24 ( such maximal extension being , e . g ., approximately 8 mm of the leader 80 ), the motor 188 is driven clockwise and the arm 216 rotates clockwise so as to disengage the planetary gear 196 from the sprocket gear 200 and engage with the cam gear 208 . following this , the motor 188 is driven to rotate in the opposite ( e . g ., clockwise ) direction as shown in fig8 d . thus , there is a resulting clockwise rotation of the cam gear 208 which causes the cam 212 to correspondingly rotate and thereby bias the pivot assembly 160 away from the threading frame 88 in a clockwise pivoting action about the pivots 164 . moreover , the motor 188 rotates the cam gear 208 until a sensor interrupt flange 224 ( fig7 ), that is attached to the upper cam surface 228 , rotates into a position wherein this flange interrupts a light beam emitted from a light - emitting sensor ( not shown , but in one embodiment , residing adjacent the motor surface 228 of fig7 ; however , the sensor is mounted to the threading frame 88 ). in particular , the light beam emitted by the light - emitting sensor is directed in the direction of a light - receiving sensor , wherein this light - receiving sensor is operatively connected to the controller for thereby deactivating the motor 188 when light is no longer sensed . note that as shown in fig8 e , such deactivation takes place when the cam 212 is in a position for substantially maximally pivotally biasing the pivot assembly 160 clockwise away from the threading frame 88 . thus , the pivoting action induces the hook subassembly 94 to move toward the pin 56 such that the pin is between the hook opening 118 and the threading track 176 . thus , with the pivot assembly 160 remaining in the clockwise pivoted position , the arm 216 is again pivoted about the shaft 186 in a counterclockwise direction so that the planetary gear 196 disengages from the cam gear 208 and engages the sprocket gear 200 . consequently , the electronic controller activates both the motor 188 to rotate the drive gear 196 in the clockwise direction , and a motor ( not shown ) of the take up reel assembly 40 for winding the leader 80 thereabout . thus , the sprocket gear 200 and the sprockets 204 also rotate in a clockwise direction thereby causing the hook subassembly 94 to engage the pin 56 , and more particularly , cause each of the pin slots 60 to enter a corresponding hook interior 124 and seat against the corresponding pin hook closed end 126 . subsequently , as the sprockets 204 continue to pull the leader 80 along the leader path 82 ( and the opposite end of the leader is correspondingly wound about the take up reel assembly 40 ), the pin 56 and the attached magnetic tape 28 are threaded through the tape drive 20 . note that it is an aspect of the present invention that the leader 80 ( and more particularly the threading bands 98 ) preferably be somewhat stiff , albeit flexible enough to wind about the take up assembly 40 . in particular , such stiffness facilitates accurate movement and positioning of the hook subassembly 94 during the grasping and ungrasping of the pin 56 . in one embodiment of the present invention , a leader stiffness of approximately 50 newtons per square millimeter has been found effective for reliably hooking and unhooking the pin 56 , plus , retaining sufficient flexibility to properly wind the leader about the take up reel hub 42 . however , it is believed that a leader stiffness in the range of 50 to 70 newtons per mm 2 may be used in various embodiments of the present invention . note that once the hook subassembly 94 passes the sprockets 204 , detection by a sensor provides the electronic controller with an input that causes it to instruct the motor 188 to deactivate . thus , the pivot assembly 160 remains in the fully pivoted position until , e . g ., the tape 28 is rewound about the cartridge hub 32 , and the pin 56 and hook subassembly 94 are decoupled . also , note that once the hook subassembly 94 passes the sprocket 204 during the threading process , the leader 80 and the tape 28 continue to be threaded through the tape drive 20 by the winding of the leader about take up assembly 40 . fig1 shows a configuration of the tape drive 20 , wherein the leader 80 has threaded the data storage tape 28 through an initial portion of the tape path through the tape drive . in particular , this figure shows the tape 28 threaded up to approximately the read / write head 38 . it is further noted that since the interior of the leader path 82 is open between the threading tracks 176 a and 176 b , the magnetic tape 28 follows a shorter path through the tape drive 20 . for example , in fig1 , the magnetic tape 28 is shown taking a shorter path than that of the leader path 82 between the open end 220 of the leader path and the read / write head 38 . the path of the tape is constrained and defined by the following components of the tape drive 20 ( fig1 and 10 ): ( a ) a first tape guide 240 ( being , e . g ., a low friction hydrodynamic bearing , in one embodiment manufactured from a ceramic composite ), ( b ) a first tape cleaning blade 244 for removing debris from the tape 28 , ( c ) the read / write head 38 , ( d ) a second tape cleaning blade 248 , and ( e ) a second tape guide 252 ( being also , in one embodiment , a hydrodynamic bearing ). note that the tape 28 is shown following the path defined by these components in fig1 . further note that the tape path is designed to accommodate high tape speeds through the tape drive 20 , such as a tape speed of 10 meters per second . in particular , the hydrodynamic bearings 240 and 252 are intended to facilitate such high tape speeds without damaging or tearing the tape 28 . referring now to the take up assembly 40 , it includes : ( a ) the take up reel hub 42 ( fig1 and 12 ) for winding the tape 28 thereabout ; ( b ) a motor 256 ( fig1 ) for winding both the leader 80 and the data storage tape 28 about the reel assembly 40 ; ( c ) two pairs of tape alignment flanges 260 a and 260 b ( fig1 ), wherein each of the pairs 260 a and 260 b includes a pair of substantially co - planar flanges 264 on opposite sides of the take up reel hub 42 , wherein each such pair 260 a and 260 b are parallelly spaced apart from the other two substantially co - planar flanges 264 included in the other pair of 260 a and 260 b . note that the pairs of 260 a and 260 b are parallelly spaced apart only marginally more than the width of the magnetic tape 28 ; ( d ) two leader take up reels 270 a and 270 b , wherein each of the threading bands 98 of the leader winds about a different one of the leader take up reels . note that in the embodiment shown in , e . g ., fig1 , the leader take up reel 270 a is manufactured as a unit with the pair 260 a of tape alignment flanges , and the leader take up reel 270 b is manufactured as a unit with the pair 260 b of tape alignment flanges . the take up reel hub 42 includes outer caps 274 a and 274 b ( e . g ., fig1 ) which secures therebetween the tape winding core 280 about which the magnetic tape 28 winds on the surface 284 . note that each of the outer caps 274 a and 274 b has a cutout 296 therein , wherein the cutouts receive at least part of a core door mechanism 288 ( also denoted simply as “ door ” herein ) that pivots between : ( a ) a closed position ( fig1 and 15 ), wherein the arcuate surface 292 , in combination with the arcuate surface 284 , completes the cylindrical or circumferential surface about which the tape 28 winds when it is wound about the take up reel hub 42 ; and ( b ) an open position ( fig1 and 10 ), wherein an interior of the cutout 296 is accessible via the opening 300 ( fig1 ). additionally , note that pin 304 ( fig1 ) secures the door 288 in the cutout 296 . in particular , the pin 304 extends through hole 308 in the door 288 so that the door pivots on this pin . during the threading of the tape 28 through the tape drive 20 , each of the threading bands 98 winds around a corresponding one of the leader take up reels 270 a and 270 b to which the threading band is attached . note that prior to the pin 56 contacting the take reel hub 42 , the door 288 is biased in an open position by a spring 310 and remains open during the rotation of the take up reel assembly 40 until the spring bias is overcome as will be discussed hereinbelow . subsequently , since the length of the leader 80 and its attachment positions on the leader take up reels 270 a and 270 b are such that when the hook subassembly 94 and the attached pin 56 reach the take up reel hub 42 , the subassembly hook and the pin enter the opening 300 and the pin lodges against the ledge 314 ( fig1 and 14 ). note that the ledge 314 is interior to the cylindrical surface composed of the surfaces 284 and 292 about which the tape 28 winds . subsequently , the tape 28 commences to wind about the surface 284 of the tape winding core 280 until the surface 292 of the open door 288 is encountered . accordingly , the tape 28 then commences to follow the surface 292 as shown in fig1 . since the typical tension on the magnetic tape 28 during this tape threading process is approximately one newton , prior to the magnetic tape reaching the free end 318 ( fig1 and 14 ) of the door 288 , the tape tension overcomes the bias of the spring 310 and the door 288 closes thereby enclosing the hook 94 and the pin 56 within the take up reel hub 42 . thus , a substantially smooth and uniform circumferential surface ( i . e ., the combined surfaces 284 and 292 ) is provided for winding the magnetic tape 28 thereabout , since the tape does not contact any of : the leader 80 , the hook subassembly 94 , and the pin 56 . regarding the unwinding of the tape 28 and the leader 80 from the take up reel assembly 40 , this process is substantially the reverse of the winding process described immediately above . that is , once the innermost layer of the tape 28 wrapping the combined surfaces 284 and 292 unwraps past approximately the midway point along the surface 292 of the door 288 , the bias of the spring 310 overcomes the counter - bias of the tape and the door 288 opens thereby allowing the pin 56 and the hook subassembly 94 to freely exit the interior of the take reel hub 42 . thus , once the pin 56 detaches from the take up reel hub 42 , the leader bands 98 commence unwinding from the leader take up reels 270 a and 270 b . fig1 - 19g show an alternative embodiment of the take up reel hub 42 , wherein an alternative configuration of the door mechanism or simply door ( labeled 288 a ) and related components are shown . referring to fig1 and 17 , the take up reel hub 42 is substantially identical to the initial embodiment of the take up reel hub provided hereinabove . however , instead of the door being substantially outside of the tape winding core 280 when in the open position , the door 288 a is substantially interior to the tape winding core when the door is open when as shown in fig1 . in particular , the surface 292 , upon which the tape winds when the door 288 a is closed , it is entirely within the tape winding core 280 . the door 288 a has a first pivot shaft 350 centered on an axis 354 about which the door pivots ( according to rotation arrow 356 , fig1 ). the first pivot shaft 350 is attached to the first door plate 358 . the first door plate 358 extends from a free end 362 to an opposite end that is attached to ( or integrally molded with ) the generally arcuately shaped door face component 366 which has the surface 292 as a “ front side ”, and an opposing “ back side ” having a reinforced portion 370 to which the first door plate 358 is attached . additionally , note that there is a second door plate 374 having the same shape as the first door plate 358 , wherein the two plates are aligned such that when viewing them along the axis 354 , their profiles are identical . moreover , each of the first and second door plates 358 and 374 are similarly attached to the reinforced portion 370 . additionally , although not shown , the second door plate 374 has attached to its side 378 ( entirely hidden in the views of fig1 and 17 ) a second pivot shaft 350 that is substantially identical to the first pivot shaft 350 . however , the second pivot shaft 350 extends away from the side 378 along the axis 354 in the opposite direction from which the first pivot shaft 350 extends from the first door plate 358 . the first and second door plates 358 and 374 are parallelly spaced apart but attached to one another by a post 382 that traverses the space between the two door plates . note that the post 382 is offset from the axis 354 so that when the door 288 a pivots about the axis 354 , the post follows a circular path about the axis 354 . moreover , as an aside , note that there may be additional posts connecting the first and second plates 358 and 374 together as one skilled in the art will understand . attached to the post 382 is a spring 386 , wherein the spring extends between the post and a spring fastener 390 attached to the tape winding core 280 within a cutout 394 . during the rotation of the door 288 a between the fully open position of fig1 and the fully closed position of fig1 , the post 382 follows an arcuate path 396 ( fig1 ) about the axis 354 . accordingly , the spring 386 changes position and configuration as the post moves along the arcuate path 396 . in particular , the spring has sufficient tensile strength to bias the post 382 to the end points 398 and 402 of the arcuate path 396 . accordingly , the spring urges the door 288 a to either enter and stay in a fully open position , or enter and stay in a fully closed position . thus , if the door 288 a is open and is urged to close so that the post 382 travels clockwise to a position beyond the midpoint of the path 396 , then the door 288 will , from that position on , be biased by the spring 386 to fully close . conversely , when the door 288 a is in the fully closed position and is subsequently urged to open so that the post 382 travels counterclockwise past the midpoint of the path 396 , then the door will be biased by the spring 386 to fully open . fig1 a - 19g illustrate the closing of the door 288 a at the completion of the threading of the tape 28 through the tape drive 20 . accordingly , in fig1 a , the door 288 a is shown in its fully open position while the take up reel hub 42 rotates in the direction of arrow 406 . accordingly , no portion of the tape 28 encounters the take up reel hub 42 . instead , the threading bands 98 of the leader 80 are being wound about the leader take up reels 270 a and 270 b . ( note , each of the take up reels are substantially identical to those shown in the initial embodiment ; in particular , the take up reels 270 a and 270 b of fig1 . further , note that for simplicity the tape alignment flange pairs 260 a and 260 b are not shown in fig1 - 19 g ). in fig1 b , a portion of the arcuately shaped door component 366 has entered the space between the threading bands 98 of the leader 80 due to the winding of the threading bands about the leader take up reels 270 a and 270 b . in fig1 c , as the take up reel hub 42 continues to rotate , the door 288 a contacts the pin 56 which is coupled with the hook subassembly 94 . note that as with the previous embodiment 288 a of the door , the length of the leader 80 is such that when substantially fully wound around the leader take up reels 270 a and 270 b , the coupling of the pin 56 and the hook subassembly 94 is positioned for contacting the door 288 a as shown in the present figure . accordingly , this contact causes the door 288 a to commence pivoting clockwise about the first and second pivot shafts 350 . in fig1 d , the door 288 a is shown pivoting further in the clockwise direction , wherein the post 382 has rotated away from the initial end point position of 398 ( fig1 ). note that it is an aspect of the present invention that for the portion of the profile of the first and second door plates 358 and 374 where the pin 56 contacts this profile , the profile is smooth and shaped so that the force induced on the door 288 a by the pin does not induce a force in the direction of the pivot shafts 350 that could cause the door to bind on the shaft pins or break the shaft pins . in fig1 e , the pin 56 has caused the door 288 a to pivot sufficiently so that the post 288 is substantially at a midway position between the positions 398 and 402 ( fig1 ). thus , the spring 386 is in a substantially maximally extended configuration . moreover , note that the pin 56 and the hook subassembly stay 114 have begun to enter the recess 410 between : ( a ) the door plates 358 and 374 on the one side , and ( b ) the arcuately shaped door face component 356 on the other side . in fig1 f , the position of the post 382 is such that the spring 386 is biasing the door 288 a to close . accordingly , the door 288 a will close without further urging by the pin 56 . thus , the backside of the arcuately shaped door face component 366 now contacts the pin 56 due to the spring 386 now urging the door 288 a closed . moreover , note that the pin 56 is now fully within the recess 410 . however , note that since both the pin 56 and the hook subassembly 94 extend substantially from the leader take up reel 270 a to the leader take up reel 270 b , the pin and hook subassembly extend outside of the tape winding core 280 in the direction of the axis 354 ( fig1 ). in fig1 g , the door 288 a is shown fully closed . accordingly , the tape 28 now extends : ( a ) from the pin 56 within the interior of the cylindrical tape winding surface provided by the combination surfaces 284 and 292 , ( b ) through the tape exit 414 , which may be no more than a mating of the end 418 of the door 288 a with the tape winding core 280 , and ( c ) to the exterior of the take up reel hub 42 . note that the tape 28 now commences to wind around the circumferential combinations of arcuate surfaces 284 and 292 . when the tape 28 is being unwound from the take up reel hub 42 and the tape is to be unthreaded from the tape drive 20 , the illustrations of fig1 a - 19g occur in reverse order . however , note that the tension on the tape itself during the unwinding process is now used to urge the door 288 a open and thereby overcome the door closing bias of the spring 386 . thus , as the take up reel hub 42 rotates in the clockwise direction for unwinding the tape , the tape 28 causes the door 288 a to rotate counterclockwise about the pivot shafts 350 , and the pin and hook subassembly are released from the interior of the tape winding core 280 . the foregoing discussion of the invention has been presented for purposes of illustration and description . further , the description is not intended to limit the invention to the form disclosed herein . consequently , variation and modification commensurate with the above teachings , and within the skill and knowledge of the relevant art , are within the scope of the present invention . the embodiments described hereinabove are further intended to explain the best modes presently known of practicing the invention and to enable others skilled in the art to utilize the invention as such , or in other embodiments and with the various modifications required by their particular application or uses of the invention . it is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art .