Sequence expressions and assignments

A sequence expression describes a sequence or a set of sequences. Sequence expressions include:

• A sequence filename, a literal sequence, or a variable representing the value of a sequence expression.

• A reference to a single sequence in a multi-sequence file by path/name, name or number.

• A fragment (subrange) of a sequence, where each coordinate is specified by a “site expression” (also see Integral Expressions).

• A concatenation of sequence expressions.

• A function of a sequence expression, such as complement, cut, extract or translate.