There is a complex per-chain column to the left of other per-chain columns, defined by
AMINO=x1,...,xn: display amino acid columns for the given categories, in one combined ordered
group, where each xi is one of:

┌────────┬───────────────────────────────────────────────────────────────────────────────────────┐
│cdr1    │  CDR1 sequence                                                                        │
│cdr2    │  CDR2 sequence                                                                        │
│cdr3    │  CDR3 sequence                                                                        │
│fwr1    │  FWR1 sequence                                                                        │
│fwr2    │  FWR2 sequence                                                                        │
│fwr3    │  FWR3 sequence                                                                        │
│fwr4    │  FWR4 sequence                                                                        │
│        │  Notes:                                                                               │
│        │  1. Please see the page on bit.ly/enclone about V(D)J features for notes              │
│        │  on our method and interpretation.                                                    │
│        │  2. There are circumstances under which these cannot be calculated, most notably in   │
│        │  cases where something is wrong with the associated reference sequence.  In such      │
│        │  cases, even though you specify CDR1 or CDR2, they will not be shown.                 │
│        │  3. If the CDR1 and CDR2 sequences are sufficiently short, the part of the header line│
│        │  that looks like e.g. ═CDR1═ will get contracted e.g. to DR1 or something even more   │
│        │  cryptic.  It is also possible that the computed CDR1 or CDR2 is empty.               │
│        │  4. The same stipulations apply to FWR1, FWR2 and FWR3.                               │
│        │  5. Spaces are shown between features unless NOSPACES is specified.                   │
├────────┼───────────────────────────────────────────────────────────────────────────────────────┤
│var     │  positions in chain that vary across the clonotype                                    │
│share   │  positions in chain that differ consistently from the donor reference                 │
├────────┼───────────────────────────────────────────────────────────────────────────────────────┤
│donor   │  positions in chain where the donor reference differs from the universal reference    │
├────────┼───────────────────────────────────────────────────────────────────────────────────────┤
│donorn  │  positions in chain where the donor reference differs nonsynonymously                 │
│        │  from the universal reference                                                         │
├────────┼───────────────────────────────────────────────────────────────────────────────────────┤
│a-b     │  amino acids numbered a through b (zero-based, inclusive)                             │
└────────┴───────────────────────────────────────────────────────────────────────────────────────┘

Note that we compute positions in base space, and then divide by three to get positions in amino
acid space.  Thus it can happen that a position in amino acid space is shown for both var and share.

The default value for AMINO is cdr3,var,share,donor.  Note that we only report amino acids that
are strictly within V..J, thus specifically excluding the codon bridging J and C.