Fastly VCL provides various arithmetic and conditional operators.

Operator precedence defines the order of operations when evaluating an expression. Higher precedence operators are evaluated before those with lower precedence. Operators are listed in the following table, highest precedence first. For example, a || b && c reads as a || (b && c) because && has higher precedence than ||.

This is a companion discussion topic for the original entry at https://developer.fastly.com/reference/vcl/operators

There’s no mention of the : operator on this page, and I think there should be, since it’s in “VCL best practices”: VCL best practices | Fastly Developer Hub