3.6.23 WHILE - Conditionally loop over a Template Block

Conditionally repeated block. Its arguments are evaluated (see EXPR - Evaluate and emit an Expression) and as long as the result is non-zero or a string with one or more bytes, then the condition is true and the text from that point until a matched ENDWHILE is emitted.

[+WHILE <full-expression> +]
emit things that are for the true condition[+

ENDWHILE +]

<full-expression> may be any expression described in the EXPR expression function, including the use of apply-codes and value-names. If the expression yields an empty string, it is interpreted as false.