Unable to print out an Attribute value via Macro?

I want to print out a character's Action Point value in the same roll template used to attack and to parry. AP is a value that decreases each time you take an action in a combat round, and a round continues until every participant has reached 0. After that everyone's AP resets and a new round begins. Ideally, I want to take a character's current value and subtract it by one before printing it out but it seems I'm not allowed to do that. Am I doing something wrong or is this a feature I need a Pro subscription to use?

From the first image, it looks like your action_points attribute only has a value in the max field.  Try using:

@{selected|action_points|max}

Changing the value of an attribute can only be automated with the API, which is a Pro Subscriber Perk.

Your suggestion returned this in the chat:
Rolf has ((ceil(((13+0)+(14+0))/12)+0)+0) left.

action_points has four different variables used for calculations in the character sheet, action_points, action_points_std, action_points_temp and fatigue_action_points. As I understand it, action_points is the maximum value derived from std + temp * fatigue. std is the value derived from character attributes, temp is a box you can input whatever in the sheet and fatigue is a modifier that screws over your character with several levels.

Looking inside the html for the sheet there are also a different set called attr_action_points etc and a unique attr_action_points_max but they all return a "No attribute was found for" error.

EDIT:
selecting action_points_std in the token puts the value in the other field, but putting it in the macro returns ceil(((13+0)+(14+0))/12), removing the two parenthesis before ceil. SOrry for double editing, it's 4am and my eyes are swimming

No worries.  So, that attribute is a formula attribute, you just need to surround it in [[ ]] to evaluate it into the value:

[[@{selected|action_points|max}]]

Thank you, that worked. Even if I can't automatically alter the value it's a good reminder to have. I already change it manually for every token so now it should be easier to catch when I do forget.

I have been sitting with the wiki documentation all night and I am very sure that I haven't seen any mention of formula attributes or any examples resembling what you just showed me. If it actually isn't there perhaps it should be added.

That's a good point.  It's sort of hard to know where to put it.  The fact that it's a formula is a function of the character sheet, so putting it there makes sense.  But If you don't know about them (I guess, technically it's called and "auto-calc field"), you wouldn't know to look there.  Probably somewhere with attribute references would make sense to just note it.

Added it here: https://wiki.roll20.net/Macros#Attributes_and_Char...