All commands within mib2c.conf files are embraced by @ signs. Anything with an @ sign at the front and back of the line is generally supposed to be a mib2c specific command. These are detailed here: COMMANDSHERE
Variables in the mib2c language look very similar to perl variables, in that they start with a "$". They can be used for anything you want, but most typically they'll hold mib node names being processed by @foreach ...@ clauses.
They also have a special properties when they are a mib node, such that adding special suffixes to them will allow them to be interpreted in some fashion. The easiest way to understand this is through an example. If the variable 'x' contained the word 'ifType' then some magical things happen. In mib2c output, anytime $x is seen it is replaced with "ifType". Additional suffixes can be used to get other aspects of that mib node though. If $x.objectID is seen, it'll be replaced by the OID for ifType: ".1.3.6.1.2.1.2.2.1.3". Other suffixes that can appear after a dot are listed below.
One last thing: you can use things like $vartext immediately ending in some other text, you can use {}s to get proper expansion of only part of the mib2c input. IE, $xtext will produce "$xtext", but ${x}text will produce "ifTypetext" instead. VAREXPANSIONSHERE
mib2c(1)