asterisk users - Dec 2005 - Variables naming, may be a BUG??

Hi,
i discovered that in version 1.2.0 stable if i use a variable like:

CALLERID_FOO=12345

in the extension.conf, the variable is not evaluated and left empty.
In the 1.0.9 it was not this way.
May be a bug?
Bye,
Marcello