X30 Subfield $k - Form subheading:
Subfield $k contains a form subheading used in a uniform title heading. Form subheadings used with uniform titles include Manuscript, Protocols, etc., and Selections.
Examples:
130 #0 $aBible.$pO.T.$pFive Scrolls.$lHebrew.$sBiblioteca apostolica Vaticana.$kManuscript.$nUrbaniti Hebraicus 1
130 #0 $aConvention for the Protection of Human Rights and Fundamental Freedoms$d(1950).$kProtocols, etc.
130 #0 $aPortrait and biographical album of Isabella County, Mich.$kSelections