19. The computer program product of claim 17 wherein means, recorded on the recording medium, for identifying a recording period within a presentation session further comprises means, recorded on the recording medium, for logging on by the first user during the presentation session.
17. A computer program product for differential dynamic content delivery, the computer program product comprising: a non-transitory recording medium; means, recorded on the recording medium, for providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; means, recorded on the recording medium, for identifying a recording period within a presentation session; means, recorded on the recording medium, for recording, during the recording period, a first presentation control instruction; means, recorded on the recording medium, for selecting from the session structured document a first classified structural element in dependence upon the recorded first presentation control instruction and in dependence upon user classifications of a first user participant in the presentation; means, recorded on the recording medium, for presenting the first classified structural element to the first user on a first display device; selecting from the session structured document a second classified structural element in dependence upon a second presentation control instruction and in dependence upon user classifications of a second user participant in the presentation; and presenting the second classified structural element to the second user on a second display device.