The term editor has special features for handling certain kinds of sequences of terms . It makes sequences appear much like terms with variable numbers of subterms. The kinds of sequences supported are described below.
Sequences are constructed by the right-associated use of pairing terms. Each kind of sequence has its own pairing term, and also a special term to represent the empty sequence. Eventually, we'll relax the right-association restriction. Often there is no need to distinguish between a term and a one element sequence containing that term. So, in specific contexts, the editor treats a term as a one element sequence. These contexts are pointed out at relevant points in this document.
The term tree cursor motion commands skip over this internal structure, and for nearly all purposes the internal structure of sequences can safely be ignored.