The information stored in the header section of a SAM file.
See http://samtools.github.io/hts-specs/SAMv1.pdf - Section 1.3.
The struct sam-header has a default constructor make-sam-header.
Accessor sam-header-hd of type property list refers to the @HD line.
Accessor sam-header-sq of type list of property lists refers to the @SQ lines.
Accessor sam-header-rg of type list of property lists refers to the @RG lines.
Accessor sam-header-pg of type list of property lists refers to the @PG lines.
Accessor sam-header-co of type list of strings refers to the @CO lines.
Accessor sam-header-user-tags of type property list refers to lines defined by end users.
All information in property lists are stored in the same order as they occur in a SAM file.