LTP in stage lighting stands for Latest Takes Precedence.
What this means is that regardless what value a channel is set at, a signal that is sent using LTP will overide what is all ready there. i.e. the “latest” signal is the one that will be used.
For example if channel 1 has a DMX value of 128 and you send a LTP DMX value of 175 the new value for the channel will be 175. It has been overidden. If a new LTP DMX signal is sent on the same channel it will take that value.