Alternation Syntax

The v3 alternation syntax of %{foo:-bar} is no longer necessary, and has been removed.

The new approach is simpler and clearer, just use short-circuit ||: in an expression.

Old Style - no longer supported

&Reply-Message := "Hello %{%{User-Name}:-none}"

New Alternation

&Reply-Message := "Hello %{&User-Name || 'none'}"

This approach also means that nested alternation is no longer necessary:

Old Style - no longer supported

&Reply-Message := "Hello %{%{NAS-Identifer}:-%{%{User-Name}:-none}}"

New Alternation

&Reply-Message := "Hello %{&NAS-Identifier || &User-Name || 'none'}"

Unlike version 3, any strings used in || alternation must be quoted. Numbers and IP addresses do not need to be quoted.