Or the same question can be asked as: what's a better name: tag1 or tag-1? Depending on if underscores are disallowed, or dashes are disallowed.

While we are on the topic of dashes vs underscores, check out when to capitalize HTML classes, and when to keep ids in Pascal Case.

In HTML, classes should be lower-case with dashes:

<div class="class-name-1 another-class-name"> </div>

There are exceptions:

<div class="BookChapter" ></div>

However, ids should be camelCase or PascalCase (capitalized first letter):

<div id="thisDiv"></div><div id="anotherArray"></div>

Just throwing two cents here - if the pandemic taught us 10 things, one of those ten gotta be that small details in communication matter very much. With that, I recommend renaming the word "criticality" -> "priority". The reasoning is as follows. And be careful with the red color in the smart sheet too, please, for the same reason. 

This one is pretty easy. Between suffixes (namespaces), roots (what a thing actually is), and suffixes and all that, I like to use a suffix (a word-final thing, something that goes at the end of the word) that denotes the type of the thing (name, variable) being used. It probably sounds more complicated than it really is so here are some clarifying examples.

The following examples are either variable names, or properties of an object, or fields of a model, or methods in a class, or keys in a hash. Hopefully you get the idea.