For example
 
;https://www.autoitscript.com/wiki/Best_coding_practices#Names_of_Variables
Global $idL = GUICtrlCreateInput("3", 16, 48, 25, 22, $ES_NUMBER)
Global $idP = GUICtrlCreateInput("3", 56, 48, 25, 22, $ES_NUMBER)
$idGo = GUICtrlCreateButton("Start", 136, 48, 83, 25)
Global $idM = GUICtrlCreateInput("1", 96, 48, 25, 22, $ES_NUMBER)
Case $idGo
         $iL = Number(GUICtrlRead($idL))
         $iP = Number(GUICtrlRead($idP))
         $iM = Number(GUICtrlRead($idM))
         
         ConsoleWrite(" l: " & $iL & " p: " & $iP & " m: " & $iM & @LF);