The reading structure holds the primary information stored for each sequence. It references several other structures by their numbers into their own structure index. The reading structures also contain references to other reading structures. This is done by use of a doubly linked list ("left" and "right" fields), sorted on ascending position within the contig.
io_write_readingio reading_number keyed_list_contents
For a description of the readinf structure, see (FIXME) "The GReadings Structure".