Is there a word for a character being a number, letter, or underscore? [closed]

Edit: Close this question as it doesn’t relate to English.

I know the term "alphanumeric" means a character is a letter or number, but is there a term that includes underscores? So _, A, and 9 would all fit this definition.

The exact characters that fit this definition are as follows: a-z, A-Z, 0-9, _ (and no non-English letters like â, é, ł, or anything else that isn’t in the normal English alphabet)

The following characters do not fit this definition: &, /, ~, â, +.

The following characters do fit this definition: A, b, 4, _, 9, z

Example context (missing term is x):

• "_ah7" contains all x characters.
• "hg8&" contains non-x characters.

I've tried searching this up, but all the results are irrelevant garbage.

Quick thing to add: Yes, it is reasonable that a term like this exists because almost every single programming language that is based on English allows identifiers to be alphanumeric characters or underscores where the first character is not a number. This is consistent among thousands who know different languages- the better question would be why isn't it a term already (if it isn't)?

No there isn't.

In English, "underscore" has no special significance. In fact in English Language terms underscore isn't really recognized as a character - it was originally used in typewriters, where the typist would do underlining by typing the text, backspacing over it, and then typing underscores over the characters. It was carried over to to telex and computer character representations, and is now pretty much used only in computer programming. It isn't officially classed as 'punctuation' in English.

Every grouping that includes letters, digits and underscore is extremely specialized in that it applies to a specific computer language. Each language or application may define a technical term to for the grouping, but it would be specific to that application. So the usage is not frequent enough to have acquired a common name.