It sounds awkward but it was a common way of expressing the time allocated for a programmes time on air versus others. The more popular programmes get the best time slice when most people are watching the television at home and the less popular shows/programmes accordingly are shown other times when less viewers are using their tv for active entertainment. In other word the idea of time allocation. To go back to my first sentence: in the past when computer terminology was not popular nowadays they mix into other areas too. Example: a CPU has time allocations (time slices)
for programms (not ProgrammEs) or also older CPU with slots for connection replaced nowadys by 478/775 pin connectors etc. Prior to all this the word time slot was used the way I tried to describe before concerning tv-programmes. I think it is more US eng. to use slot not so much Uk. Eng.


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Note added at 2 hrs (2007-12-08 23:21:40 GMT)
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Also programme block could work. Tv movie time must be allocated and added along to the tv series programm block. Here instead of slot the word block means time slice/allocated.

...series (or serial) type of program(me).

Just another option that rings natural in English. I also agree with Paul's "program(me) category".