I have had different specs depending on what channel my work has been shown at, but generally the specs used by Swedish National TV (SVT) have been functioning practically everywhere else too.
That specs was, as I recall, an upper hard limit on -6dB and a nominal level of about -12 to -16dB SPL A-Weighted. There are many more than that, but the rest of 'em are more or less about keeping an even quality of the material.
Frankly the SPL didn't seem all that important as long as it's within reasonable limits, I only brought my SPL-meter (a Dolby Meter 2-plugin) just about a year ago and worked all by ear before that (actually mostly do now too, but it's good to have a clear reference of where you are!), just being careful not to let it be too low.