was not possible to access frames other than the top level frame directly (i.e., in this case pages other than "7471a"). This follow-on frame facility was exploited extensively by the implementation of telesoftware on Prestel whereby computer programmes, notably for the BBC Micro, were available for download from Prestel. Generally speaking, the first two or three frames acted as header pages. For example, one such programme was described on frame 70067a, and 70067b, while frame 70067c gave the number of subsequent frames containing the programme, and a crosscheck sum. Special software enabled this crosscheck sum to be compared with a value calculated from the result of downloading all the required frames in order to verify a successful download. The actual telesoftware programme was contained from frame 70067d onwards, in this case for a further ten frames. In the event that the check failed it was necessary to download the entire programme again starting from the beginning. Each frame had a single-character type code associated with it. Most frames would be "i" (for "Information" types) but other types included response frames, mailbox pages, or gateway pages. Special frame types could also be specified which caused the follow-on frame to be automatically displayed, with or without the usual clear-screen code, as soon as the current frame had finished being transmitted. These were mainly used by "dynamic frames", as it provided a mechanism to continue animations which would not otherwise fit within the number of characters available in a standard frame. Views Information providers There were two levels of information provider (IP) – firstly a "Main IP" who rented pages from Post Office Telecommunications (PO)/British Telecom (BT) directly, and thus owned a three-digit node or "master page" in the database. This required an ongoing investment, consisting of a minimal annual payment to become an information provider. The price of this basic package was £5,500 per annum in 1983, equivalent to around £29,000 in 2021. The charge included: the facility to enter and amend information and to retrieve response frames 100 frames capacity to store 10 completed response frames editing training for staff (two-day seminar) copy of IP editing manual; annual print-out of frames in use (if required) bulk update facilities (if required). Additional frames were available in batches of 500 for £500 per annum (over £2,600 in 2021) while Closed User Groups and Sub-IP Facility cost respectively £250 (over £1,300 in 2021). Those