On the Growth and Trimming of the L Trees of MeSH.

This was accomplished by reviewing the first L Tree, introduced in 1960, to see what terminology was originally included. The major revisions to the L Tree, which occurred in 1963, 1965, 1966, 1975, and 1987, were then studied to ascertain the degree and nature of the changes made to the terminology. Fifty titles, selected randomly from the 1992 Symposium on Computer Applications in Medical Care (SCAMC) papers, were reviewed to identify terms used in these titles that also appeared in the 1992 L Tree.