This directory contains programs which convert data files from 
pre-Y2K format to the corresponding Y2K format and vice versa.

Hypocenter and First Motion solution programs:

1.  HYPOINVERSE	(older NCSN catalog and phase data)
	USGS program that computes hypocenters and magnitudes given phase
	arrivals and amplitude readings.  The original version of this program
	and its output files are NOT Y2K compliant.  The hypoinverse output
	solution files represnets dates with 2 digit years.
	The older NSCN catalog used HYPOINVERSE format for its catalog and
	phase files.

2.  HYP2000	(current NCSN catalog and phase data)
	The current version of the original HYPOINVERSE program that is Y2K
	compliant.  The output solution files from HYP2000 represent dates
	with 4 digit years.  The current NCSN catalog uses HYP2000 format
	for its catalog and phase files.  The output format from HYP2000
	also provides more digits for other fields such as magnitudes.

3.  FPFIT	(NCSN first motion data)
	The NSCN first motion solutions are created by a program FPFIT.
	The original FPFIT program was not Y2K compliant in that sense that
	it stored dates with only 2 digit years.  The current version of
	FPIT stored dates with 4 digit years.  This is the only change
	in the output file format of FPFIT.


Data formats used at the NCEDC:

1.  NSCN catalog format
	The NCSN catalog format (also know as "sum" or "summary" format)
	was originally stored in HYPOINVERSE format files, and is
	now stored in HYP2000 format files.  The catalog entries
	are merely the hypocenter lines that have been extracted from
	the full phase format files described below.

2.  NCSN phase format
	The NCSN phase format (also known as "arc" or "archive" format)
	was originally stored in HYPOINVERSE format files, and is now
	stored in HYP2000 format files.  The file contains (for each
	event)
	    a.	hypocenter line
	    b.  phase and amplitude readings
	    c.  "shadow cards" for (a) and (b) which contain additiona
		information not used or computed by HYP2000.

3.   NCSM Mech (first motion) format
	The NCSN first mechanism files (also known as "mec", "mech", or
	"fpfit" format) are stored in the Y2K version of FPFIT format files.
	The original versions of the mechanims files were stored in
	the pre-Y2K FPFIT format files which had on ly 2 digit years.

Conversion Programs:

1.  2000sum.f

	The program 2000arc.f will convert older HYPOINVERSE summary (sum)
	files to HYP2000 summary (sum) format.  This can be used to convert
	older format NCSN catalog data to current Y2K compatible NCSN catalog
	format.  It assumes all date are in the 20-th century [1900-1999].

2.  2000arc.f

	The program 2000arc.f will convert older HYPOINVERSE phase (archive)
	files to HYP2000 phase (archive) format files.  This can be used to
	convert older format NCSN phase data to current Y2K compatible NCSN
	phase format.

3.  cvarc.c
	The program cvarc.c will convert current Y2K compatible NCSN
	catalog or phase files back to older non-Y2K format HYPOINVERSE
	format files.

4.  cvmec.c
	The program cvmec.w will convert current y2K compatible NCSN
	Mech (y2K FPFIT) format files back to older non-Y2K format
	mech files.