Grass Valley Profile XP Aug 16 2004 - Manual (Page 211)

Selecting audio reference level
23 July 2004 Profile XP System Guide 211
Selecting audio reference level
The audio reference level is used by Profile applications to scale audio level meters.
Setting the audio reference level determines the absolute value at 0db.
To set the audio reference level, select Audio Reference Level in the Configuration
Manager window, then select the audio reference level used at your facility.