acc - GenBank accession number.
def - Definition (one line description).
key - keyword list (semicolon separated lower case).
src - Source.  Often the organism or tissue.
org - Organism.  Standard Latin binomial form.
aut - Authors field.  Comma separated.
jou - Journal.
lib - Clone library.
clo - Clone.
sex - Sex.
tis - Tissue type.
dev - Developmental stage.
cel - Cell line.
cds - CDS (Coding region).
gen - Gene name.
pro - Product (name of protein associated with gene).
cno - Note associated with CDS.
mol - Molecule type (mRNA, DNA, etc.)
cat - Database category (also known as GenBank division) (EST, HTG, PRI, etc).
dat - Date submitted to GenBank.
dir - Direction of EST clone (3' or 5')
pha - Phase of HTGS.  Either 0, 1, 2, or 3.  Corresponds to HTGS_PHASE0,
      HTGS_PHASE1, etc.  Phase 0, 1, and 2 may have gaps.  Phase 0 and 1
      are unorders.
cen - Sequencing center.  May be Sanger, Whitehead, etc.
frg - Number of fragments (contigs) in sequence.