readRCV1(...)function with the signature elem, language, load, id:list with the two named elements content
and uri. The first element must hold the document corpus to
be read in, the second element must hold a call to the document
corpus. The call is evaluated upon a request for load on demand.character giving the text's language.logical value indicating whether the document
corpus should be immediately loaded into memory.character representing a unique identification
string for the returned text document.XMLTextDocument representing
content.