A word may be correct only if always lower-case. Spell-checking permits words to get capital initials at beginnings of sentences. This capitalization should be suppressible for particular words, such as some computer commands for Unix, Linux, and BSD.
Steps to Reproduce:
1. Check that your LO spelling checker's user-defined dictionary does not include the following: dd
2. In a Writer document, type the following: Dd dd
3. Run spell-check (F7).
This passes the spell-check.
Since the term is correct only for all lower-case because using any other case when entering the command in a command-line interface (especially with older distributions of Linux), "Dd" should be rejected as a misspelling even though it's at the beginning of the sentence.
User Profile Reset: No
For a few words, only the literal entry in the custom dictionary would be approved in a document.
The suppression should be available for words in the main dictionary as well as in custom dictionaries. Suppression even in the main dictionary would be by the user's choice.
While I use a Linux distro for which the CLI tentatively recognizes the initial capital for a Linux command (it suggests proceeding with the lower-case alternative), arguments and options are often case-sensitve to the point of assigning different meanings for different cases, and for that situation spell checker suppression would help with Writer.
The UserProfile doesn't seem to be available for resetting.
OpenGL doesn't seem to be available for enabling.