Almost all parameters are optional, some are however needed to result in a meaningful user interface.
You wanted to show a chart, stating the item name seemed required for you, however what period did you intend to show? Unlimited? If not, a setting would be required, don’t you agree?
And if you think that something is missing in the documentation, YOU can file a change via a pull request. This is an open source project!
I agree, needing a period makes sense in this case. But, what indication is there that that particular one IS required? Is it not possible that it has some sort of default, thus falls into the “Almost all” category. Obviously the item can’t have a default, begin/end/legend apparently do.
Indeed, I can and could. But, I’m far from comfortable with OH in general or it’s documentation style to assume I’m qualified.
For something like this if you were confused and now understand. You are very well qualified to know if there is a sentence or two that could be added or changed that would have avoided the confusion. You don’t have to be an expert to contribute, and all contributions are reviewed so you can’t break something.