340 - Physical Medium

Physical Medium is defined in BF&S as "Physical description information for an item that requires technical equipment for its use, and/or more granular description information of an item's material properties to facilitate access and discovery or to support collection management." 

There is a lot of information that can be put into the 340 that also goes in various other parts of the MARC record. We aren't going to go into the specifics, but if it seems like you have seen some of this elsewhere, you probably have and that's fine as it is appropriate in multiple places.

There are 17 different kinds of physical aspects of an item (so far) for which a specific subfield of the 340 tag has been defined. All subfields are repeatable within the tag and the tag is also repeatable which allows for a lot of detail to be included. For most of the tags there are RDA lists from which the terms must be taken. Definitions below are mine, the terms link to the official definitions which also include links to the relevant lists of authorized terms.

ǂa	Material base and configuration	What is it physically made of (concrete, silk, videotape)?
ǂb	Dimensions	The size in time (a 90 min. audio) or space (a 3x5 card)
ǂc	Material applied to surface	Physical substance applied to the base (crayon, albumen)
ǂd	Information recording technique	How did the info get on it (typed, x-rayed, stamped)?
ǂe	Support	What holds it up? A wood frame for example.
ǂf	Reduction ratio value	Size in relation to original it duplicates as a number (3X or 16:1)
ǂg	Color content	Black & white or b&w with one color; or multicolored
ǂh	Location within medium	Where in the larger work is it (page number, audio track)?
ǂi	Technical specifications of medium	What is needed to view it (model X microfilm reader)?
ǂj	Generation	Relationship to other versions (film master, duplicate)?
ǂk	Layout	The arrangement of text, images, etc. (double-sided)
ǂl	Binding	How is it bound (spiral binding, saddle-stitched, etc.)
ǂm	Book format	How was the paper folded pre-printing? (folio, quarto)?
ǂn	Font size	May be general (large print) and/or specific (24 pt.)
ǂo	Polarity	Relationship of reproduced colors and tones to the original
ǂp	Illustrative content	General info and/or specifics about the included pictures
ǂq	Reduction ratio designator	Size in relation to original it duplicates in words not ratios

This tag has been fussed with quite a bit during the 21st century. Several subfields were "new" in 2011, one subfield was "renamed" and the tag was "redescribed" in 2022. I know this because the Library of Congress MARC documentation includes "Content Designator History" at the end which explains how the tag has changed over time. BF&S doesn't include this data, but there is usually a link at the bottom of the entry for a particular tag to the LC documentation where you will find it.

Since this is the last Tuesday of the month it is time for the July 2024 Tuesday Tags Review Quiz. This is a 5-question self-check that will give you a chance to see how much you have learned about MARC tags this month (or where you may want to go back and re-read).