Blend APIs requires Guids to be lowercase? Is that correct?

I like to confirm this, as it has tripped me up a number of times when setting up unit test and working with Postman.

Since SQL Server stores guids as uppercase and C# treats them as lowercase, within C# code this is not an issue, so long as you don't treat them as strings. But, if you pull in the guids from SQL, which are always uppercased, and use those for Postman tests, they will fail.

I just want to confirm this, as guids are not case sensitive. But the Blend APIs seem to be.

Best regards,
Jon