LC has changed the form subdivisions for specific types of maps (e.g. "$vMaps, Topographic") to "$vMaps". LC's rationale is that the specific form data should be found in a 655 field. See the LC CDS announcement for details.
To avoid the loss of useful information, LTI now adds a genre/form heading to the bibliographic record to retain the specific map data. E.g., When "$vMaps, Topographic" is changed to "$vMaps", the field "655 0$aTopographic maps" is added to the bib record.
No earlier than March 1, 2011, LC intends to reissue genre/form authority records. At that time, LTI will switch over to 655 7 |a[Term].|2lcgft in accordance with LC's revised practice.
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