An Item number is composed of up to 4 items. Type, Issue_Number, Variation, Printing. If all 4 are used it would be:
Type Number/Variation-Printing
Example using all four: Bk 1/A-2
Not all need to be used.
1 Issue Number only
1/A Issue Number with Variation
1-2 Issue Number with Printing
1/A-2 Issue Number with Variation and Printing
1-2 Issue Number with Printing
Bk 1 Type with Issue Number
Bk 1/A Type with Issue Number and Variation
Bk 1/A-2 Type with Issue Number and Variation and Printing
(There are other combinations)
Punctuation is:
A Space between Type and Issue Number (Bk 1)
A Slash between Issue Number and Variation (1/A, 1/HC, etc.)
A Dash between Issue Number (or Variation if used) and Printing (1-2, 1/HC-2)