The tables reported below are extracted from the Appendix A of rinex300.pdf and describe the content of the RINEX Product file.
TABLE A1 GNSS OBSERVATION DATA FILE - HEADER SECTION DESCRIPTION
HEADER LABEL (Columns 61-80)	DESCRIPTION	FORMAT
RINEX VERSION / TYPE	- Format version : 3.00 - File type: O for Observation Data - Satellite System: G: GPS R: GLONASS E: Galileo S: SBAS payload M: Mixed	F9.2,11X, A1,19X, A1,19X
PGM / RUN BY / DATE	- Name of program creating current file - Name of agency creating current file - Date and time of file creation Format: yyyymmdd hhmmss zone zone: 3-4 char. code for time zone. UTC recommended! LCL if local time with unknown local time system code	A20, A20, A20
*COMMENT	Comment line(s)	A60
MARKER NAME	Name of antenna marker	A60
*MARKER NUMBER	Number of antenna marker	A20
MARKER TYPE	Type of the marker: GEODETIC : Earth-fixed, high-precision monumentation NON_GEODETIC : Earth-fixed, low-precision monumentation NON_PHYSICAL : Generated from network processing SPACEBORNE : Orbiting space vehicle AIRBORNE : Aircraft, balloon, etc. WATER_CRAFT : Mobile water craft GROUND_CRAFT : Mobile terrestrial vehicle FIXED_BUOY : "Fixed" on water surface FLOATING_BUOY: Floating on water surface FLOATING_ICE : Floating ice sheet, etc. GLACIER : "Fixed" on a glacier BALLISTIC : Rockets, shells, etc ANIMAL : Animal carrying a receiver HUMAN : Human being Record required except for GEODETIC and NON_GEODETIC marker types. Users may define other project-dependent keywords.	A20,40X
OBSERVER / AGENCY	Name of observer / agency	A20,A40
REC # / TYPE / VERS	Receiver number, type, and version (Version: e.g. Internal Software Version)	3A20
ANT # / TYPE	Antenna number and type	2A20
APPROX POSITION XYZ	Geocentric approximate marker position (Units: Meters, System: ITRS recommended) Optional for moving platforms	3F14.4
ANTENNA: DELTA H/E/N	- Antenna height: Height of the antenna reference point (ARP) above the marker - Horizontal eccentricity of ARP relative to the marker (east/north) All units in meters	F14.4, 2F14.4
*ANTENNA: DELTA X/Y/Z	Position of antenna reference point for antenna on vehicle (m): XYZ vector in body-fixed coord. system	3F14.4
*ANTENNA: PHASECENTER	Average phase center position w/r to antenna reference point (m) - Satellite system (G/R/E/S) - Observation code - North/East/Up (fixed station) or X/Y/Z in body-fixed system (vehicle)	A1, 1X,A3, F9.4, 2F14.4
*ANTENNA: B.SIGHT XYZ	Direction of the “vertical” antenna axis towards the GNSS satellites. Antenna on vehicle: Unit vector in body-fixed coord. system Tilted antenna on fixed station: Unit vector in N/E/Up left-handed system	3F14.4
*ANTENNA: ZERODIR AZI	Azimuth of the zero-direction of a fixed antenna (degrees, from north)	F14.4
*ANTENNA: ZERODIR XYZ	Zero-direction of antenna Antenna on vehicle: Unit vector in body-fixed coord. system Tilted antenna on fixed station: Unit vector in N/E/Up left-handed system	3F14.4
*CENTER OF MASS: XYZ	Current center of mass (X,Y,Z, meters) of vehicle in body-fixed coordinate system. Same system as used for attitude.	3F14.4
SYS / # / OBS TYPES	- Satellite system code (G/R/E/S) - Number of different observation types for the specified satellite system - Observation descriptors: - Type - Band - Attribute Use continuation line(s) for more than 13 observation descriptors. In mixed files: Repeat for each satellite system. These records should precede any SYS / SCALE FACTOR records (see below). The following observation descriptors are defined in RINEX Version 3.00: Type: C = Code / Pseudorange L = Phase D = Doppler S = Raw signal strength I = Ionosphere phase delay X = Receiver channel numbers Band: 1 = L1 (GPS,SBAS) G1 (GLO) E2-L1-E1 (GAL) 2 = L2 (GPS) G2 (GLO) 5 = L5 (GPS,SBAS) E5a (GAL) 6 = E6 (GAL) 7 = E5b (GAL) 8 = E5a+b (GAL) 0 for type X (all) Attribute: P = P code-based (GPS,GLO) C = C code-based (SBAS,GPS,GLO) Y = Y code-based (GPS) M = M code-based (GPS) N = codeless (GPS) A = A channel (GAL) B = B channel (GAL) C = C channel (GAL) I = I channel (GPS,GAL) Q = Q channel (GPS,GAL) S = M channel (L2C GPS) L = L channel (L2C GPS) X = B+C channels (GAL) I+Q channels (GPS,GAL) M+L channels (GPS) W = based on Z-tracking (GPS) (see text) Z = A+B+C channels (GAL) blank : for types I and X (all) or unknown tracking mode All characters in uppercase only! Units : Phase : full cycles Pseudorange : meters Doppler : Hz SNR etc : receiver-dependent Ionosphere : full cycles Channel # : See text Sign definition: See text. The sequence of the observations in the observation records has to correspond to the sequence of the types in this record of the respective satellite system. The attribute can be left blank if not known. See text!	A1, 2X,I3, 13(1X,A3) 6X, 13(1X,A3)
*SIGNAL STRENGTH UNIT	- Unit of the signal strength observables Snn (if present) DBHZ : S/N given in dbHz ...	A20,40X
*INTERVAL	Observation interval in seconds	F10.3
TIME OF FIRST OBS	- Time of first observation record (4-digit-year, month,day,hour,min,sec) - Time system: GPS (=GPS time system) GLO (=UTC time system) GAL (=Galileo System Time) Compulsory in mixed GNSS files Defaults: GPS for pure GPS files GLO for pure GLONASS files GAL for pure Galileo files	5I6,F13.7, 5X,A3
*TIME OF LAST OBS	- Time of last observation record (4-digit-year, month,day,hour,min,sec) - Time system: Same value as in TIME OF FIRST OBS record	5I6,F13.7, 5X,A3
*RCV CLOCK OFFS APPL	Epoch, code, and phase are corrected by applying the realtime-derived receiver clock offset: 1=yes, 0=no; default: 0=no Record required if clock offsets are reported in the EPOCH/SAT records	I6
*SYS / DCBS APPLIED	- Satellite system (G/R/E/S) - Program name used to apply differential code bias corrections - Source of corrections (URL) Repeat for each satellite system. No corrections applied: Blank fields or record not present.	A1, 1X,A17, 1X,A40
*SYS / PCVS APPLIED	- Satellite system (G/R/E/S) - Program name used to apply phase center variation corrections - Source of corrections (URL) Repeat for each satellite system. No corrections applied: Blank fields or record not present.	A1, 1X,A17, 1X,A40
*SYS / SCALE FACTOR	- Satellite system (G/R/E/S) - Factor to divide stored observations with before use (1,10,100,1000) - Number of observation types involved. 0 or blank: All observation types - List of observation types Use continuation line(s) for more than 12 observation types. Repeat record if different factors are applied to different observation types. A value of 1 is assumed if record is missing.	A1, 1X,I4, 2X,I2, 12(1X,A3) 10X, 12(1X,A3)
*LEAP SECONDS	Number of leap seconds since 6-Jan-1980 as transmitted by the GPS almanac. Recommended for mixed GLONASS files	I6
*# OF SATELLITES	Number of satellites, for which observations are stored in the file	I6
*PRN / # OF OBS	Satellite numbers, number of observations for each observation type indicated in the SYS / # / OBS TYPES record. If more than 9 observation types: Use continuation line(s) This record is (these records are) repeated for each satellite present in the data file	3X, A1,I2.2, 9I6 6X,9I6
END OF HEADER	Last record in the header section.	60X

Records marked with * are optional

TABLE A2 GNSS OBSERVATION DATA FILE - DATA RECORD DESCRIPTION
DESCRIPTION	FORMAT
EPOCH record - Record identifier : > - Epoch : - year (4 digits) - month,day,hour,min (two digits) - sec - Epoch flag 0: OK 1: power failure between previous and current epoch >1: Special event - Number of satellites observed in current epoch (reserved) - Receiver clock offset (seconds, optional)	A1, 1X,I4, 4(1X,I2.2), F11.7, 2X,I1, I3, 6X, F15.12,
Epoch flag = 0 or 1: OBSERVATION records follow - Satellite number - Observation \| repeat within record for each observation - LLI \| type (same sequence as given in the - Signal strength \| respective SYS / # / OBS TYPES record) This record is repeated for each satellite having been observed in the current epoch. The record length is given by the number of observation types for this satellite. Observations: Definition see text. Missing observations are written as 0.0 or blanks Phase values overflowing the fixed format F14.3 have to be clipped into the valid interval (e.g add or subtract 10**9), set LLI indicator. Loss of lock indicator (LLI). 0 or blank: OK or not known Bit 0 set : Lost lock between previous and current observation: Cycle slip possible. For phase observations only. Bit 1 set : Half-cycle ambiguity/slip possible. Software not capable of handling half cycles should skip this observation. Valid for the current epoch only. Signal strength projected into interval 1-9: 1: minimum possible signal strength 5: average S/N ratio 9: maximum possible signal strength 0 or blank: not known, don't care Standardization for S/N values given in dbHz: See text.	A1,I2.2, m(F14.3, I1, I1)
Epoch flag 2-5: EVENT: Special records may follow - Epoch flag 2: start moving antenna 3: new site occupation (end of kinem. data) (at least MARKER NAME record follows) 4: header information follows 5: external event (epoch is significant, same time frame as observation time tags) - "Number of satellites" contains number of special records to follow. 0 if no special records follow. Maximum number of records: 999 For events without significant epoch the epoch fields in the EPOCH RECORD can be left blank	[2X,I1] [I3]
Epoch flag = 6: EVENT: Cycle slip records follow - Epoch flag 6: cycle slip records follow to optionally report detected and repaired cycle slips (same format as OBSERVATIONS records; - slip instead of observation; - LLI and signal strength blank or zero)	[2X,I1]