Yes, it’s the correct way. Knowing that it’s the correct way involved knowing the internal details. The documentation should be updated to mention (or be clearer about) what properties are available.
It’s probably mentioned in the syntax documentation. Generally, the only case-insensitive thing are command names (the part before the first open parentheses on each line). Variable names, properties, genex names, targets, test names, etc. are certainly case-sensitive.