A question about the variable Slot

Each type of variable has a different slot size.
What is the size (in bits) for each type?
Where can I find the help documentation for this?
How does the bit alignment mechanism or slot merging mechanism work?

No file, test, or entry point is named. First clarify whether the request concerns compiler implementation details or user documentation, then locate the relevant variable-slot documentation and define the requested slot sizes, alignment rules, and merging behavior as the completion criteria.

Written by the indexing model from the issue text.