Multiple questions regarding IF statements and variables in Templates

[KF-Dale]

1) Is there a list of the variables that are available in the templates, I am already aware of this list but there are a few variables that I have seen used in configs that are not listed here. I want to know if I can get the group IDs for the extension, or the outbound caller ID.

2) Can I test variable output to see exactly what they give? For example does %%extension_number%% give just the digits, as I think it does - or anything else e.g. spaces.

3) How do the {IF} blocks work, I was trying to do my own such as the below:

{IF %%extension_number%% =400}
        <P2917>%%PROVLINKLOCAL.HOST%%:%%PROVLINKLOCAL.PORT%%%%PROVLINKLOCAL.PATH%%/logotest/1.jpg</P2917>
        {ELSE}
        <P2917>%%PROVLINKLOCAL.HOST%%:%%PROVLINKLOCAL.PORT%%%%PROVLINKLOCAL.PATH%%/logotest/2.jpg</P2917>
    {ENDIF}

but this doesn't work? The parameter is unchanged in the web console of the phone. I would ideally like to specify the logo based on the outbound caller ID, or the Group ID assigned to the phone. Do the blocks also support any kind of "ELSEIF"


This is using the following environment:
3CX Server Version: 15.5.15502.6
GrandStream GXP2160 Firmware: 1.0.9.108