Confused about bibliography in old books I’ve been looking at the bibliography of an old book called History Of Burma by G. E. Harvey and am quite confused.
There are abbreviations introduced first like this: 


  B Bodleian Library
  BM British Museum
  IO India Office Library


An example for an actual citation is: 


  John Stevens, The Portuguese Asia, three vols 1695.
  
  B 55.b.59-61.
  BM 582.e.6, 8.
  IO 300.A.76.H.10-12


I can see the abbreviations refer to respective libraries, but what about the numbers? Are they referring to the book’s location in the library, or pages within the book itself?
A quick search of the current Bodleian catalogue turns up this record.

Selecting the 'find &amp; request' tab indicates that the three volumes are still available with call numbers 55.b.59-61. Thus, it would appear that the bibliography is specifying call numbers in the different libraries (much as modern bibliographies list DOIs!).