# 11. Lexical syntax¶

For an overview of the lexical syntax, see Lexical syntax in the QL language specification. In particular, you can find the list of QL keywords, the different kinds of identifiers, and a description of comments.

All standard one-line and multiline comments, as described in the QL language specification, are ignored by the QL compiler and are only visible in the source code. You can also write another kind of comment, namely QLDoc comments. These comments describe QL entities and are displayed as pop-up information in QL editors. For information about QLDoc comments, see the QLDoc specification.

The following example uses these three different kinds of comments:

/**
* A QLDoc comment that describes the class Digit.
*/
class Digit extends int {  // A short one-line comment
Digit() {
this in [0 .. 9]
}
}

/*
A standard multiline comment, perhaps to provide
additional details, or to write a TODO comment.
*/