In CCDPACK the positions of identified/detected image features
are stored in ordinary text files which are referred to as
`position lists'. The format of these lists is flexible. Usually
position lists have three columns: these may be separated by
commas or blanks. The identifier is an integer value which is
used to identify positions which are related (i.e. are of the
same object) in different lists.Identifier X-position Y-position
If more than three columns exist then only the values in the
first three are used, though some of the programs propagate
extra columns from the input to the output lists. If only two
columns exist it is assumed that they are: such lists may be
produced by KAPPA applications. In this case applications which
rely on a knowledge of the identifiers assume they are
monotonically increasing from one.X-position Y-position Whole
and in-line comments are allowed in position lists using the
character `#'. These are not propagated from input to output
lists. Note that the final line of the f