I'm not a native English speaker, so I'm often wrong when it comes to grammar. I usually go with my gut feeling.
I'm documenting some parts of an application and I was reminded that I often omit the the article in my sentences. So we started discussing individual cases but I was objecting to my very best knowledge why the should not be part of them but I'm not sure.
I would still like to write them correctly even though none of us are native speakers.
The donut chart is used ...
I wrote it without the article because in my understanding the refers to noun chart which in this case is well defined by the word donut so I would say it doesn't need an article. And it's about a donut chart that is the only one on the component I'm documenting.
The chart slice sizes are ...
I also omitted the article, but in the end I think my sentence was wrong, because article here refers to slice sizes and I should actually wrote it as Chart's slice sizes and of course without the article.
top part with the date period selector
This is the whole text of some bullet point. I omitted the article because it refers to a specific selector. A date period selector specifically.
Etc... As said, this is all very fuzzy to me.