A BBC Programme Identifier (PID) is an alphanumeric, persistent, unique identifier for a television or radio programme brand, a season or series, or an individual episode, used by the BBC in their web URLs, iPlayer viewers, and internal databases.
If the PID begins with the letter "b", this means the content reference identifier (CRID) authority is Red Bee; an opening "p" means that the authority is the BBC's Programme Information Pages (PIPs) database.
Other sources, denoted by different opening letters, could potentially be introduced.
[6] An example, in the "p" range, is the PID for the 1956 Desert Island Discs episode featuring Ada Cherry Kearton, p009y95q.
[7] The BBC encourages viewers and listeners to machine tag media relating to programmes, on social sites such as Flickr and their own blog posts, using the relevant PID, in the format bbc:programme=b048l0g3.