Names sometimes have a meaning.
LMSR? left right mid side momentary short term?
The majority of our mixing is in stereo.
As you might know, in stereo there are two channels called Left and Right.
Maybe the L and R in LMSR might have the meaning of Left and Right?
Left and Right can be expressed as (and mathematically translated to) Mid and Side.
Although Mid and Side signals are used for some mixing purposes, they are nothing else as Left and Right with a little bit of math.
Absolute levels are from utter importance, especially in the digital domain.
As far as auditory perception is concerned, the concept of loudness is much more important.
Loudness and dynamic range are the major concepts when it comes to mastering.
Short term and Momentary max. levels according to a standardized measuring method give a clue of the dynamic and overall loudness of a track.
Most metering apps/plugins have a combined meter, that shows Left and Right levels and the loudness range as a combination of momentary and short term levels.
20230131 TG