> .so[2-11] /my/source/file with spaces in the name The idea that the argument of .so might contain unquoted spaces is anathema--contrary to groff convention and fortunately not supported. I think the idea of selecting lines from a file is good, but it doesn't warrant new groff syntax. I would prefer
.so file firstline lastline For a one-line inclusion "lastline" might be omitted, but I think that case is too rare to merit the extra language burden. Doug