Property names follow some simple guidelines that aim to help you memorize properties.
The shortest name always gives a nice human-readable summary of an item. For example, Mission yields a ship's mission in text form ("Tow a ship"). By adding more words, you can ask for details. For example, Mission.Tow yields the "Tow" parameter of the mission. Alternatively, adding a dollar sign gives the internal representation. For example, Mission$ yields the mission number (7).
For programming, writing search queries, etc., you will probably use the "$" forms most often. For formatting text, you will most likely use the short standard form.
When you define your own names, it makes sense to give them a unique prefix to avoid clashes with others' names (in case you're using scripts developed by others).
Internally, PCC uses some names starting with CC$. Those names are undocumented and subject to change without notice. You should not use them. Currently, many keybindings are implemented using a CC$ name. If you want to modify such a keybinding, it's best to copy the existing one. For example, as of beta 9, the "change primary enemy" function (E on ship screen) is implemented as CC$ChangePE. To assign this function to the P key, you should write
Bind Ship "p" := Key(Ship, "e")
instead of Bind Ship "p" := "CC$ChangePE". This is guaranteed to keep working in future versions.
