FREE-FORMAT HEADER

If a 'free-format' header is used, the header and TOAs are either in
separate files or are combined into a single file.

If a single file is used, the file contains, in order:
   1.  A line with the keyword 'HEAD'.
   2.  Free-format header parameters and control cards.
   3.  A line with the keyword 'TOA'.
   4.  TOA lines.

If two primary files are used, the TOAs are listed in the <file>
given in the tempo command line.  The header parameters are in
'<file>.par'.  If <file> has an extension, '.par' replaces it; if
not, '.par' is appended.

Free-format header entries have the format 'keyword value [flag]',
with one keyword per line.  There are two types of keyword, for
control parameters and pulsar parameters, respectively. Space(s) or
tab(s) separate items in an entry.  Characters following the value
are ignored.  Keywords are case-insensitive, and characters in
keywords beyond those given in the parameter list are ignored.

Flags are used to indicate whether or not a parameter is to be
fitted.  Flags must be one and only one character. For keywords
representing parameters of the fit, a flag value of 0 (the default)
indicates the parameter should not be fit, while a flag vale of 1
indicates the parameter should be fit.  In a few special cases flag
values above 1 indicate fitting of several, closely associated
parameters. For values above 9, the hex character is used.  Flags are
not used for most control keywords.  Exceptions are 'START' and
'FINISH':  these keywords are ignored unless the associated flag
value is nonzero.

Each time TEMPO is run, an output file giving the results of the fit
and their errors is produced. This file ('<psrname>.par' in the
working directory) has the same format as the input file and may be
used as an input file. (The errors are ignored for TEMPO input.)