Comments allow you to explain, to yourself and/or to your users, what the query is trying to achieve, how it works, who wrote it or amended, etc.

Use "//" or "—" (without the double quotes) to end a line with a comment or to have the comment on its own line.

You can also use “/* COMMENT */” (again without the quotes) to insert a comment in the middle of a
line. You are also able to type anything after the command.

This heavily-commented example returns all the products beginning “MidasJ”:
//Comment number 1
/* this is another comment */
{TM1FILTERBYPATTERN( //and another comment
-- and another comment
{TM1SUBSETALL( [Product] )},/* this is yet another comment */ "MidasJ*")}
You seem to be able to type what you like here, but treat with caution

This does not work in version 8.2.7 but does in at least 9.0 and 9.1.1.