1B4

If a publication is in more than one volume and the title proper of each volume includes a designation such as numbering that is specific to that volume, add in square brackets after the first designation a hyphen and the final designation, omitting intermediate designations.

Quinti Horatii Flacci Epistolarum liber primus[-secundus]

If it is not practicable to do this, transcribe the title proper of the first volume without this addition and make a note about the later designation(s).

Describe an item in several physical parts from the chief source of information for the first part. If the first part is not available, use the first part that is. If there is no discernible first part, use the part that gives the most information. Failing this, use any part or a container that is a unifying element. Show variations in the chief sources of information of subsequent parts in notes, or, when so instructed, by incorporating the data with those derived from the first part.

DCRB requires recording volume designations found in the title; AACR2 does not, although AACR2 probably would give the same result since it provides for transcription of grammatically inseparable information.

DCRB does not specify that the description is to be based on the first volume, as AACR2 does.

At first glance, 1B4 appears to contradict 1A2, which says to omit this information unless it is "an inseparable part." 1B4 does not talk about inseparability. This could be easily remedied.

1B4 does not explicitly tell the cataloger what to do—i.e., he/she is to transcribe the first designation (as well as the last).

The omission from DCRB of instructions to describe based on the first available volume would be more appropriate in 1A2, second paragraph, than here, since 1B4 is a rule for transciption, not for sources of information.

When would it "not be practicable to do this"?

Add, after "to that volume," ", and the designation is grammatically inseparable from the title proper (cf. 1A2), transcribe the designation and"

Add to the second paragraph of 1A2 the AACR2 wording about describing from the first available part.