Mostly from fdatap.h

The NMRPipe header is 2048 bytes. It is essentially a 512 element array of 4-byte floats. However, some of the contiguous floats are actually recast into char's for storing strings. Integer metadata is simply recorded as floats. fdatap.h defines named constants to provide a key-value lookup using the array indices.

Two notes. One, the actual data sizes of the file appear to be given by array elements 99, 219, 15 and 32, corresponding to FDSIZE, FDSPECNUM, FDF3SIZE and FDF4SIZE. Two, the "correct first point" C1 value and the ZF sizes appear to be negated. (Array elements: 108, 404, 409, 418, 423, 437, 438 and 439)

Array Index	Name	Comment
0	FDMAGIC	Should be zero in valid NMRPipe file
1	FDFLTFORMAT	Constant defining floating point format. (IEEE or VAX).
2	FDFLTORDER	Constant for determining endieness. 2.345 is correct.
3-8	unused
9	FDDIMCOUNT	Number of dimensions in complete data
10	FDF3OBS	Obs Freq MHz.
11	FDF3SW	Sweep Width Hz.
12	FDF3ORIG	Axis Origin (Last Point), Hz.
13	FDF3FTFLAG	1=Freq Domain 0=Time Domain.
14	FDPLANELOC	Location of this plane; currently unused
15	FDF3SIZE	Number of points in dimension.
16-17	FDF2LABEL	8-char Axis Label.
18-19	FDF1LABEL	8-char Axis Label.
20-21	FDF3LABEL	8-char Axis Label.
22-23	FDF4LABEL	8-char Axis Label.
24	FDDIMORDER1	Dimension stored in X-Axis.
25	FDDIMORDER2	Dimension stored in Y-Axis.
26	FDDIMORDER3	Dimension stored in Z-Axis.
27	FDDIMORDER4	Dimension stored in A-Axis.
28	FDF4OBS	Obs Freq MHz.
29	FDF4SW	Sweep Width Hz.
30	FDF4ORIG	Axis Origin (Last Point), Hz.
31	FDF4FTFLAG	1=Freq Domain 0=Time Domain.
32	FDF4SIZE	Number of points in dimension.
40	FDDMXVAL
41	FDDMXFLAG
42	FDDELTATR
45	FDNUSDIM	Unexpanded NUS dimensions.
50	FDF3APOD	Current valid time-domain size.
51	FDF3QUADFLAG
53	FDF4APOD	Current valid time-domain size.
54	FDF4QUADFLAG
55	FDF1QUADFLAG
56	FDF2QUADFLAG
57	FDPIPEFLAG	Dimension code of data stream.
58	FDF3UNITS
59	FDF4UNITS
60	FDF3P0
61	FDF3P1
62	FDF4P0
63	FDF4P1
64	FDF2AQSIGN
65	FDPARTITION	Slice count for server mode. Added for NMRPipe
66	FDF2CAR
67	FDF1CAR
68	FDF3CAR
69	FDF4CAR
70	FDUSER1
71	FDUSER2
72	FDUSER3
73	FDUSER4
74	FDUSER5
75	FDPIPECOUNT	Number of functions in pipe.
76	FDUSER6
77	FDFIRSTPLANE	First Z-Plane in subset. Added for NMRPipe
78	FDLASTPLANE	Last Z-Plane in subset. Added for NMRPipe
79	FDF2CENTER	Point where carrier freq is referenced. May be outside datasize.
80	FDF1CENTER	Point where carrier freq is referenced. May be outside datasize.
81	FDF3CENTER	Point where carrier freq is referenced. May be outside datasize.
82	FDF4CENTER	Point where carrier freq is referenced. May be outside datasize.
95	FDF2APOD	Current valid time-domain size.
96	FDF2FTSIZE
97	FDREALSIZE	Number of valid time-domain pts (obsolete).
98	FDF1FTSIZE
99	FDSIZE	I.
100	FDF2SW	Sweep Width Hz.
101	FDF2ORIG	Axis Origin (Last Point), Hz.
106	FDQUADFLAG	See Data Type codes below.
108	FDF2ZF
109	FDF2P0
110	FDF2P1
111	FDF2LB
119	FDF2OBS	Obs Freq MHz.
135	FDMCFLAG	Magnitude Calculation performed.
152	FDF2UNITS
153	FDNOISE	Used to contain an RMS noise estimate.
157	FDTEMPERATURE	Temperature, K.
158	FDPRESSURE	Pressure, Pascal.
180	FDRANK	Estimate of matrix rank; Added for NMRPipe.
199	FDTAU	A Tau value (for spectral series).
200	FDF3FTSIZE
201	FDF4FTSIZE
218	FDF1OBS	Obs Freq MHz.
219	FDSPECNUM	Number of complex 1D slices in file.
220	FDF2FTFLAG	1=Freq Domain 0=Time Domain.
221	FDTRANSPOSED	1=Transposed, 0=Not Transposed.
222	FDF1FTFLAG	1=Freq Domain 0=Time Domain.
229	FDF1SW	Sweep Width Hz.
234	FDF1UNITS
243	FDF1LB
245	FDF1P0
246	FDF1P1
247	FDMAX	Max value in real part of data.
248	FDMIN	Min value in real part of data.
249	FDF1ORIG	Axis Origin (Last Point), Hz.
250	FDSCALEFLAG	1 if FDMAX and FDMIN are valid.
251	FDDISPMAX	Max value, used for display generation.
252	FDDISPMIN	Min value, used for display generation.
253	FDPTHRESH	Positive threshold for peak detection.
254	FDNTHRESH	Negative threshold for peak detection.
256	FD2DPHASE	See 2D Plane Type codes below.
257	FDF2X1
258	FDF2XN
259	FDF1X1
260	FDF1XN
261	FDF3X1
262	FDF3XN
263	FDF4X1
264	FDF4XN
266	FDDOMINFO	Spectral/Spatial Flags. Added for NMRPipe.
267	FDMETHINFO	FT/Direct Flags. Added for NMRPipe.
283	FDHOURS	Time: hours
284	FDMINS	Time: minutes
285	FDSECS	Time: seconds
286-289	FDSRCNAME	char srcFile[16] (seems blank)
290-293	FDUSERNAME	char uName[16] (seems blank)
294	FDMONTH	Date: month
295	FDDAY	Date: day
296	FDYEAR	Date: year
297-311	FDTITLE	char title[60] (seems blank)
312-351	FDCOMMENT	char comment[160] (seems blank)
359	FDLASTBLOCK
360	FDCONTBLOCK
361	FDBASEBLOCK
362	FDPEAKBLOCK
363	FDBMAPBLOCK
364	FDHISTBLOCK
365	FD1DBLOCK
370	FDSCORE	Added for screening score etc.
371	FDSCANS	Number of Scans per 1D.
372	FDF3LB
373	FDF4LB
374	FDF2GB
375	FDF1GB
376	FDF3GB
377	FDF4GB
378	FDF2OBSMID
379	FDF1OBSMID
380	FDF3OBSMID
381	FDF4OBSMID
382	FDF2GOFF
383	FDF1GOFF
384	FDF3GOFF
385	FDF4GOFF
386	FDF2TDSIZE
387	FDF1TDSIZE
388	FDF3TDSIZE
389	FDF4TDSIZE
399	FD2DVIRGIN	0=Data never accessed, header never adjusted.
400	FDF3APODCODE
401	FDF3APODQ1
402	FDF3APODQ2
403	FDF3APODQ3
404	FDF3C1
405	FDF4APODCODE
406	FDF4APODQ1
407	FDF4APODQ2
408	FDF4APODQ3
409	FDF4C1
413	FDF2APODCODE	GMB=7, SP=1
414	FDF1APODCODE
415	FDF2APODQ1
416	FDF2APODQ2
417	FDF2APODQ3
418	FDF2C1
419	FDF2APODDF
420	FDF1APODQ1
421	FDF1APODQ2
422	FDF1APODQ3
423	FDF1C1
428	FDF1APOD	Current valid time-domain size.
437	FDF1ZF
438	FDF3ZF
439	FDF4ZF
442	FDFILECOUNT	Number of files in complete data.
443	FDSLICECOUNT0	Encodes number of 1D slices in stream.
444	FDTHREADCOUNT	Multi-Thread Mode: Number of Threads.
445	FDTHREADID	Multi-Thread Mode: Thread ID, First = 0.
446	FDSLICECOUNT1	Encodes number of 1D slices in stream.
447	FDCUBEFLAG	Data is 3D cube file series.
464-471	FDOPERNAME	char oName[32] (seems blank)
475	FDF1AQSIGN
476	FDF3AQSIGN
477	FDF4AQSIGN
480	FDF2OFFPPM
481	FDF1OFFPPM
482	FDF3OFFPPM
483	FDF4OFFPPM