Attribute names - whatever their type - are:
- Case-sensitive. 'pronoun', 'ProNoun', 'Pronoun', 'PRONOUN' are all valid names that if created would be 4 discrete attributes.
- Only upper or lower case letters an numerals are allowed in attribute names. So, allowed characters: A-Z, a-z, 0-9 (and excluding commas & hyphens!). The Document Inspector's User tab for making new user attributes will suppress keyboard input for any other characters to help enforce this rule. So you may have 'ToDo' but not 'To-Do', 'To_Do' or To Do' as an attribute name. A name of '8' or '009' is allowed but probably none too useful.
Although you may use any letter case combination it is worth noting that the general style in Tinderbox - and examples in the manual etc., tend to one of two styles opening capital ('Prototype') or inter-capitalised ('AgentPriority'). For newer users, adopting the latter form for user attributes will help to distinguish attributes when seen in action and export code.
Perhaps self-evident, but adopting self explanatory names is useful both in writing codes but also when displaying key attributes.
Attributes can be renamed.
NOTE re Attribute names & the $-prefix. In action code, when an attribute's value is referred to a $-prefix is used. Thus to call the value if the attribute WordCount, $WordCount is used. To refer to the name of said attribute, use "WordCount". Within aTbRef, inline references in general text which refer to Tinderbox attributes names generally use a $-prefix as a marker that it is an attribute name being cited. The latter is a slight variance with in-app usage but does aid clarity in the articles.