PHL controller described an uncertain route event when departing traffic failed to turn as expected; the reporter noting local procedures need adjusting to clarify routing information; i.e. conventional vs. RNAV SIDS.

Narrative

I was working North Departure combined with North High; North Arrival; Yardly; and Pottstown. Air Carrier X checked in climbing to 10;000 and I RADAR identified him. Because Air Carrier X checked in climbing to 10;000; I assumed he was on the RNAV departure and expected Air Carrier X to make the appropriate turns to his departure fix. Air Carrier X didn't make any turns and instead I noticed him at 10;000 near Brand intersection (about 25 miles east of PHL). I made the point out with the appropriate sector and it was approved. There was no loss of separation. I know the RNAV departures are terminated at XA pm; so when Air Carrier X checked in climbing to 10;000 a red flag should have gone up. I think it is also important to note that later in the evening this same scenario occurred with another air carrier who checked in climbing to 10;000ft; but this time I caught it and turned the aircraft on course. Important things to know: 1. Aircraft on RNAV departures are climbing to 10;000ft. 2. Aircraft on the PHL8 departure should only be climbing to 5;000ft. I don't know if this is what happened without pulling the tapes; but this is what I think happened. Clearance Delivery issues the RNAV departures until XA:59 pm. At XA pm; RNAV departures are terminated and the Ground or Local Controller has to go back and reissue the PHL8 departure to aircraft. Sometime before XA pm; Air Carrier X was probably issued the RNAV departure; climbing to 10;000. After Air Carrier X taxied out he was probably reissued the PHL8; but was not reissued an altitude to maintain. I feel it would be better to error on the side of the PHL8 rather than the RNAV departure. My recommendation would be to have Clearance Delivery issue the PHL8 on all clearances starting at XA:30 pm. This will increase the chances of an aircraft being on the PHL8 after XA pm and it will decrease the work load of the Ground and/or Local controller.