This is a part of the struct module in the tcllib distribution.
The documentation for this package can be found at http://tcllib.sourceforge.net/doc/struct_list.html (and http://docs.activestate.com/activetcl/8.5/tcllib/struct/struct_list.html as well).
The package provides a single command, struct::list, which provides the following methods:
- assign sequence varname ? varname ? ...
- dbJoin ? -inner|-left|-right|-full ? ? -keys varname ? {keycol table}...
- dbJoinKeyed ? -inner|-left|-right|-full ? ? -keys varname ? table...
- equal a b
- filter sequence cmdprefix
- filterfor var sequence expr
- firstperm list
- flatten ? -full ? ? -- ? sequence
- fold sequence initialvalue cmdprefix
- foreachperm var list body
- iota n
- lcsInvert lcsData len1 len2
- lcsInvert2 lcs1 lcs2 len1 len2
- lcsInvertMerge lcsData len1 len2
- lcsInvertMerge2 lcs1 lcs2 len1 len2
- longestCommonSubsequence sequence1 sequence2 ? maxOccurs ?
- longestCommonSubsequence2 sequence1 sequence2 ? maxOccurs ?
- map sequence cmdprefix
- mapfor var sequence script
- nextperm perm
- permutations list
- repeat size element1 ? element2 element3 ... ?
- repeatn value size...
- reverse sequence
- shift listvar
- split sequence cmdprefix ?passVar failVar?
- swap listvar i j
The prefix lcs used by a number of the methods above stands for longest common subsequence.