The .XLOWER command allows you to control the case of index
entries specified by the .INDEX and the .ENTRY commands, or by
the Index flag (>). The case of the index entries will match
exactly the case that you enter when you make the index entry.
See also the .XUPPER command.
Format
.XLOWER
Abreviated format
.XL
1 – Default
If you do not specify the .XLOWER command, .XUPPER is the
default.