PLI - Pitch Limit Indicator; as per eckhard.
Origin was the indication of the maximum pitch attitude which is available to maximise climb performance in wind-shear; displayed on the attitude indicator.
The difference between aircraft datum (zero deg) and max pitch angle (PLI), is an indication of AoA margin for the intended use of PLI - normally stick-shake for wind-shear but over time systems and operations corrupt … …
The value of PLI - AoA margin, should reposition with change of speed, 'g'.
With more recent depictions / interpretations and switchable computations (EFIS / HUD); the PLI could indicate the wind-shear limit, EGPWS pull up, stall recovery, depend on aircraft type, operator procedures and training.
Similar to some EFIS speed tape low speed awareness symbology.