You can use a javascript check. I wrote one for my phpLD 2.0-3.5 sites. If they select a top level it pops up an error saying they need to select a subcategory.
I'd also be interested in this mod. If anyone has it and it works with phplinkdirectory 3.0.6, please share.
umm people, phpLD 3.06 HAS IT built in. try looking into your admin control panel and paying attention, rather than trying to throw up a 3 second directory for a quick buck.
There's an option in the admincp for 3.0.6 which you can enable that will require submitters to choose a category before they're able to submit their site. You can find this option by going to your admincp -> Edit Settings -> click Directory -> next to the Category selection method select the following setting from the drop down menu -> Define (no selection possible) -> click Save button. This will show the following on the submit page if the submitter has not chosen a category prior to submitting: Category: Please select a category! . To disable submitters from submitting their sites to the top level categories, you'll need a mod for this. Unfortunately I haven't found one yet.