No, not domestic science, nor is it do with musical improvisation. "What they do these jammers, is talk. they talk about the plots they're hatching. Escapes mostly, but plans and developments for all kinds of mischief. They do it to confuse the Observers. The plots they talk about are always make-believe. Non-existant. But Control can't know that until they've checked them out."
That is the discriptive dialogue given to No.6 by the exccentric artist No.118, while he paints No.6's portrait during the episode of It's Your Funeral. Jamming, when you think about it, wasn't that what No.6 was doing in the previous episode Hammer Into Anvil? I mean there was no person as XO4 to who D6 was to report, well at least as far as we know there wasn't. There was no message contained on the recording of Bizet's L'arlesienne for No.6. No secret writing whatsoever on those blank sheets of paper. No.6 wasn't heliographing with that hand mirror of his, unless it was to No.2, who was watching No.6 down on the beach on the wall screen in the Control Room. No.6 was up to mishief, Jamming if you like. Laying a false trail, leaving false clues for No.2 to follow towards his own dimise!
Be seeing you