Note
The format is identified by the extension vasp, poscar or contcar.
Alternatively, the basenames poscar and contcar identify the format as well.
Ammonia molecular crystal in pre Vasp 5 POSCAR format:
H N
1.0000000000000000
5.0133599999999996 0.0000000000000000 0.0000000000000000
0.0000000000000000 5.0133599999999996 0.0000000000000000
0.0000000000000000 0.0000000000000000 5.0133599999999996
12 4
Cartesian
2.1985588943999996 1.7639005823999998 0.8801454815999999
1.7639005823999998 0.8801454815999999 2.1985588943999996
0.8801454815999999 2.1985588943999996 1.7639005823999998
4.8411510839999998 1.6194155471999998 4.9398140088000000
4.3563090384000001 2.4998116967999997 3.6324801215999996
3.5195792543999995 1.1535741359999998 4.0840334567999994
4.0840334567999994 3.5195792543999995 1.1535741359999998
4.9398140088000000 4.8411510839999998 1.6194155471999998
3.6324801215999996 4.3563090384000001 2.4998116967999997
2.4998116967999997 3.6324801215999996 4.3563090384000001
1.1535741359999998 4.0840334567999994 3.5195792543999995
1.6194155471999998 4.9398140088000000 4.8411510839999998
1.3746131783999997 1.3746131783999997 1.3746131783999997
3.9981545999999994 1.9910559239999999 4.4636450759999997
4.4636450759999997 3.9981545999999994 1.9910559239999999
1.9910559239999999 4.4636450759999997 3.9981545999999994
Carbondioxide in POSCAR format:
4CO2
1.00000000000000
5.68032000000000 0.00000000000000 0.00000000000000
0.00000000000000 5.68032000000000 0.00000000000000
0.00000000000000 0.00000000000000 5.68032000000000
C O
4 8
Cartesian
0.94412598720000 0.94378516800000 0.95435056320000
3.71799665280000 0.95565703680000 3.73168622400000
3.71595173760000 3.71492928000000 0.96923300160000
0.95298728640000 3.72208648320000 3.72969811200000
1.62139054080000 1.61906160960000 1.63138790400000
0.26566856640000 0.26941757760000 0.27765404160000
4.39145539200000 1.63462568640000 3.05459208000000
3.04408348800000 0.27646117440000 4.40804192640000
4.39105776960000 3.04164095040000 0.28810583040000
3.03999365760000 4.38793359360000 1.64973533760000
0.27413224320000 4.40037349440000 3.05737543680000
1.63121749440000 3.04345865280000 4.40230480320000
No extension implemented to the original format.
The implementation of this format is (to our knowledge) feature-complete.
Note
Feel free to bring missing features to our attention by opening an issue.