1. Automatic equipment, to be employed in association with devices each having constituent features detectable by a radiation sensitive device, the features having only straight line boundaries and axes of symmetry, the features forming an orthogonal pattern extending parallel to orthogonal axes associated with a plane including the device features, and each device having a shape in plan enabling it to co-operate with means provided within the automatic equipment so as to be located without any angular misalignment in relation to the two orthogonal axes of the device plane, and the automatic equipment also including displacing means by which each device is displaceable within the automatic equipment, along either orthogonal axis of the device plane, and relative to co-operative parts of the automatic equipment, inspection means having a radiation sensitive device, at least considered as, being arranged to move, at a constant speed, and in relation to each device, individually, along a predetermined raster scanning path of parallel lines in a plane, parallel to the plane including the device features, there being two orthogonal axes of symmetry associated with the raster scanning pattern, one such axis being parallel to the scanning lines, and both axes being parallel to the two orthogonal axes of the plane including the device features, and the radiation sensitive device being arranged to produce signals in response to the detection of boundaries of features in the plane of the device; the inspection means also including manually adjustable marker generating means, arranged to produce associated pairs of groups of signals, with each group including at least one signal, in each raster scan period, the time interval between the signals of each such associated pair of signals representing a particular distance of movement of the radiation sensitive device, along an axis parallel to one of the two orthogonal axes of the raster scan pattern, so that each such associated pair of groups of signals represents a marker within the raster scan pattern, considered as being capable of being superimposed upon the device plane, and considered as being detactable by the radiation sensitive device, in addition to the detection thereby of the device feature boundaries, each marker representing, individually, a particular distance at a location within the raster scan pattern, each signal produced by the marker generating means representing a line in the raster scan pattern considered as being detected by the radiation sensitive device simultaneously with the production of the signal; in an initial setting operation of the automatic equipment, with an operator having determined a unique pattern of feature boundaries, in the plane of each device, the operator adjusts the marker generating means to produce a plurality of associated pairs of groups of signals, each of the associated pairs of groups of signals, considered individually, defining a location within the raster scan pattern of a determined feature boundary of the unique pattern of feature boundaries, in relation to each device positioned within the automatic equipment, and considered sequentially, the defined location of a feature boundary being considered to be a line in the raster scan pattern extending parallel to the orthogonal axis parallel to the feature boundary, and equidistant between the lines in the raster scan pattern represented by the corresponding associated pairs of groups of signals, and the adjustment of the marker generating means by the operator to be such that the feature boundary location defining line, in the raster scan pattern, is within a predetermined distance from the desired accurate location of the feature boundary in the raster scan pattern, and along an axis parallel to the orthogonal axis at right angles to the feature boundary, different markers being so adjusted in relation to different determined feature boundaries of the unique pattern of feature boundaries, each of the determined feature boundaries, individually, having a marker so adjusted in relation thereto; the automatic equipment also including discriminating means to operate upon, individually, each combination of related signals produced by the inspection means, each such a combination of related signals comprising the associated pair of groups of signals from the marker generating means corresponding to a feature boundary, together with a signal from the radiation sensitive device indicative of the detection of the feature boundary, in relation to each device, at least, coarsely positioned within the automatic equipment, as defined below, and each device being considered sequentially, the discriminating means being arranged to be capable of detecting whether, individually, each of the plurality of determined feature boundaries of the unique pattern of feature boundaries, is located within a threshold distance from the defined location of the feature boundary, and along an axis parallel to the orthogonal axis at right angles to the feature boundary, each threshold distance being at most equal to half the appropriate particular distance; the automatic equipment being set up such that when the discriminating means operates upon each combination of related signals associated with any device, and when each of the plurality of determined feature boundaries, considered individually, is detected by the discriminating means to be within an appropriate combined distance from its desired accurate location within the automatic equipment, the appropriate combined distance comprising the appropriate threshold distance plus the appropriate predetermined distance, the device is located within the automatic equipment so as to be inherently capable of co-operating with the co-operative parts of the automatic equipment, and, then, in relation to any device instantaneously being considered, when the discriminating means detects that each of the plurality of determined feature boundaries, is within the appropriate combined distance from its desired accurate location, or within the appropriate threshold distance from its defined location, the device is considered to be precisely positioned within the automatic equipment; and the automatic equipment including means whereby each of a plurality of identical devices, sequentially, and automatically, is, at least, coarsely positioned within the automatic equipment, the device being located so as not to be inherently capable of co-operating with the co-operative parts of the automatic equipment, each device being considered to be coarsely positioned when the discriminating means is capable of operating upon each combination of related signals associated with the device, but, in response, the discriminating means detecting that at least one of the plurality of determined feature boundaries is not located within the appropriate threshold distance from its defined location in the raster scan pattern; in a constituent error determining step, of a device positioning operation of the automatic equipment, the discriminating means detecting whether the device is precisely positioned within the automatic equipment, and in response to the detection by the discriminating means that the device is not so precisely positioned, the discriminating means, which is arranged to control the device displacing means, causing the displacing means to displace the device, whereby the device, at least approaches, being precisely positioned within the automatic equipment, the constituent error determining step being repeated automatically in the device positioning operation, until the discriminating means detects that the device is precisely positioned within the automatic equipment.