Comments must be started with a "c" character (case-insensitive), and followed by a space character. The comment continues to the end of the line and cannot be line-extended. Comments cannot be included in line-extended lines.
Example
c This is a comment line
+ 'a' > 'b' c This line changes "a" to "b"
+ 'c' > \
'd' c A comment here is okay too
Versions
Comments were introduced in Keyman 3.0.