Most ventless gas log burners specify "minimum gas pressure for the purpose of input adjustment".

What does "for the purpose of input adjustment" mean? This phrase is usually not used for the maximum pressure ratings, only the minimums.

Does it mean it's not a safety issue to turn the input pressure lower? Does it mean it just affects the adjustability of flames via the control on the burner? Can the flame height safely be lowered (adjusted) with the fireplace shutoff valve? Will the combustion be negatively affected if input is too low?