Looking thru your previous posts I'll guess your using Afcad to create or modify an airport??

What kind of markings do you want to create?

In Afcad the only lines you can create on an apron are those you choose in the properties for taxi links and parking connectors in the apron area.

For other lines, apron edge markings for example, you could use a narrow (1ft) apron link with centerline. These links should not be connected to any active taxi links as that could cause unforeseen results when aircraft taxi. (These unconnected links will show up as faults in the fault finder, but can be ignored.)

For more complicated markings you may have to turn to a scenery design tool like SBuilder, Airport or FSSC.

Dave