MaximumShorttermLoudnessLevel
This parameter is mandatory part of a loudness set.

Target value for Maximum Shortterm Loudness in LUFS. Value is a negative floating-point number, e.g. "-23.0". The decimal separator should always be a dot (".") and not a comma (",").
For very short audio material (less than 30 seconds), EBU R128 recommends to rely on this value (and MaximumMomentaryLoudnessLevel) and not the Integrated Loudness.
Possible values:
Default value: -20.0