I was just wondering if there's a modifier/constraint that limits an item to 1 per planet system. Also, please keep in mind that I'm new to modding SoaSE...although I'm learning quickly. 
As a bit of background...I'm trying to set up a new phase "gate" ability to put on my scout ships that will allow them to place "phase gates" in new systems they explore...but only if there isn't one there already.
Once I get this to work properly I plan to work on trying to make them into "warp gates" kinda like Star Gates...but make them have the "phase in" property...
This way they'll become kind of like worm holes, but they will still require the "phase time" and i may increase the phase time for these as well...since it'll kinda be a "special" phase. I can probably figure the rest out...I just need to know if there's a modifier/constraint to limit an item from being built in a system if there's one of that type (from that specific race ) in it.
When I looked at the posts in the Modifier List thread in the stickies I didn't notice anything that could be a constraint like this...but I may of misinterpreted what some of them do...so...any help is appreciated.
Thanks in advance!