Does an Official Supported Versions Guide Exist?

I ask this as I am noticing several errors in the Asterisk logs pertaining to the FreePBX generated conf files:

Is there a specific supported version of FreePBX for a specific version of Asterisk? Or is the latest version of FreePBX backwards-compatible with all versions of Asterisk?

I am running the latest FreePBX - 2.210.62-4 - and Asterisk 1.8.8.0. I notice errors similar to the one below occurring every time I click “Apply Changes”:

“[2013-04-15 14:18:17] WARNING[30822] pbx_config.c: The use of ‘.’ for an extension is strongly discouraged and can have unexpected behavior. Please use ‘X.’ instead at line 2944 of /etc/asterisk/extensions_additional.conf
[2013-04-15 14:18:17] VERBOSE[30822] pbx.c: – Added extension '
.’ priority 1 to ext-did-catchall
[2013-04-15 14:18:17] WARNING[30822] pbx_config.c: The use of '
.’ for an extension is strongly discouraged and can have unexpected behavior. Please use ‘X.’ instead at line 2945 of /etc/asterisk/extensions_additional.conf
[2013-04-15 14:18:17] VERBOSE[30822] pbx.c: – Added extension '
.’ priority 2 to ext-did-catchall
[2013-04-15 14:18:17] WARNING[30822] pbx_config.c: The use of ‘_.’ for an extension is strongly discouraged and can have unexpected behavior. Please use ‘_X.’ instead at line 2946 of /etc/asterisk/extensions_additional.conf”