Providing a specific entity to pending entsel

I have a third party (ARX) command that I need to use in an AutoLISP program, and the first thing the command does is an (entsel) to get an entity to work on.

Trying to figure out if there is a way that I can programmatically pass an entity to it from a selection set in my program.

I know that (entsel) can accept a point, so I can grab a point from my entity (polyline) and pass that along:

(command "_.arxcmd" (list x y z) "")

That seems to work, but passing a point is not 100% reliable to get the intended entity, as there could be another polyline (on same layer) that is overlapping, and thus might be selected instead.

Unfortunately, the "arxcmd" ignores any existing selected entities on the drawing and prompts for a new one, so I can't just preselect the entity and then issue the command. I do not have access to the arx command code.

Is there any way that I can pass the actual entity I want selected to a pending (entsel)? Or at least a trick that is more reliable than giving it a point?

have you tried to pass a entity name to the arx

Seems that the said third-part tool (ARX) is defined as a command – when call it directly on prompter should see what is his prompter asking for. If is a about a point and passing an entity name doesn’t help, then I’m afraid that you have no other solution than using a point. One work-around is to perform a zoom operation centred on selection point to maximize efficiency prior calling that tool in your code.

To test if the said command will accept an entity name try:

 (command "_.arxcmd" (car (entsel)) "")

Thank you both, the ARX command accepted an entity name, that works well.