Maple seems to change from italic to normal font when I edit a command. This results in unrecognizable parameters. For example, putting the "1" in "p1" after the following command had been typed in, resulted in an error message: implicitplot3d([p1, p2], x=-7..7,y=-7..7,z=-7..7); Error, missing operation implicitplot3d([p 1, p2], x=-7..7,y=-7..7,z=-7..7); (p 1 being pointed out, and the 1 being non-italic.) Note: p1 and p2 were defined prior to the above command as: p1:=x+y+z = 1; p2:=x+z = 0; Why is this happening, and how can it be avoided?