I can't tell you much about this programming aid other than the list of commands it offers as seen in the screenshot and the fact that it was programmed by the famous Jim Butterfield.

Append BASIC 128 is a utility for the Commodore 128 that lets you append some source code from one file to the end of another.

C128 Data Maker by Richard Best lets you convert a range of memory into Commodore 128 BASIC Data statements.  You can use this to load ML back into memory from a BASIC program.

Compactor 128 is a small utility for BASIC programs that will scan through your code and remove REM's and spaces and will also combine lines whenever possible to make the program size smaller and conserve RAM.

What can I say? This is a C128 program (80 column) that will print out a pretty looking BASIC list of a program. The source code for the program is included.