Hello bkj1,

m/p means that 

• m - if the input signal is connected to ground then is the signal TRUE
• p - if the signal is connected with +24 V (>20.7 V) then is the input signal TRUE

Please tell us a little bit more information about your question.
Information like 

• which hardware do you mean or use
• which software do you use

If you give us a lot information you became a better and more specific answer.

regards
CaOd