I think that the triangle indicate te button to push to create a FIX on some coordinates that you must enter before push.
In some aeroplanes the INS system directly inpunt contain only 10 points per time.
For directly entry point you must write the coordinates on the panel and than fix the point by clikking the function button and just after the number 1 button.
Note that if you only align the INS you read only the coordinates you're flying you must select NAV mode to insert navigation point recognizable by the LNAV of the MCP Panel.
Emanuele