The pszApp parameter and pszKey parameter are case sensitive and must match the names stored in the file exactly. There is no case-independent searching.
This function can be used before using the PrfQueryProfileString call or the PrfQueryProfileData call, to allocate space for the returned data.
No distinction is made between data that is written using the PrfWriteProfileData function and the PrfWriteProfileString function.
The maximum amount of data that can be associated with a key name is 64K bytes.