-TRAILING -ROT .
-TRAILING ( str-ptr str-len -- str-ptr str-len' )  
ansi 17.6.1.0170 <STRING>
check the given buffer if it contains whitespace at its end. If so, shorten str-len to meet the last non-whitespace character in the buffer.

reference: p4_dash_trailing in ../src/string.c:0038, export CO -TRAILING