"flight path/level-off altitude limit (T/O thrust limit)" is the limit which is set to occur to the maximum light path/level-off altitude which will enable the engine limitation to be observed to takeoff, e.g. in case of 737 the default for this is 5 minutes or the optional 10 minutes could have been purchased.
If a takeoff is performed at a thrust setting e.g. 22K at an airfield and you experience a EFTO at or near V1 thus continue the takeoff, the weight at which the aircraft can climb to MFRA, accelerate to flaps up and climb to >1500' AGL within 5 minutes is used to calculate this limit.
In performance software the administrators are capable (by manipulating the settings file) to provide this sort of information to flight-crew by displaying minimum and maximum MFRA values. Minimum MFRA will be used by crew for single engine flap retraction, maximum MFRA indicates the altitude at which in such case acceleration must have occurred in order to not bust the engine limit. The larger the gap between the two values, the more time is available. The gap is reduced for a given thrust rating when ATM is applied.