GMD stands for General Materials Description.
For pre-RDA ebrary MARC records, the General Material Designation (GMD), or “medium”, is:
– In the 245 field, following the title proper in subfield $h.
– It is enclosed in brackets.
– For ebrary ebooks, it is always “[Electronic Resource]“
For RDA records, the 245 $h subfield is replaced by fields 336, 337, and 338:
338 $aonline resource$2rdacarrier
The GMD is fixed for ebrary books, regardless of whether pre-RDA or RDA – that is, it does not vary from book to book.