It comes from an old extended Tcl library. From a hcitcl/tcl prompt
tcl> help hci/lists/lcompare
lcompare list1 list2
This command compares two lists and returns thier relation
(like strcmp 0). Corresponding elements of each list
are compared. The result is the value of the first difference
encountered or equality. A list that is a prefix of the other
list is considered to be less than the other list.
By default, items are compared lexicographically. The -numeric
flag (or some unique fraction thereof), however, causes the
items to be compared as double-precision floating-point
numbers.
.
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