The invisible attribute does not affect the filling of objects. Any text associated with a filled object will be added after the object has been filled, so that the text will not be obscured by the filling. Initially arrowhead has a value of 1. The troff output of pic is device-independent. The -T option is therefore redundant.
Objects can have an aligned attribute.
This will only work when the postprocessor is grops . Any text associated with an object having the aligned attribute will be rotated about the center of the object so that it is aligned in the direction from the start point to the end point of the object. Note that this attribute will have no effect for objects whose start and end points are coincident.