NASA Ames File Format Indices (FFI): Summary

Contents.	Notes
	Important general rules
	Remark
	Table 1.	File structure
	Table 2.	Definition of FFIs (including data & header format)
	Table 3.	Summary of header format

Notes

Tables 1, 2 & 3 below only display a summary of the different types of FFIs. Full instructions about the header and data formats for each FFI are given in Gaines & Hipskind, 1998. Data suppliers unfamiliar with NASA Ames Format are advised to refer to this last document before starting to generate their data files. The nomenclature and notation system used below are identical to the conventions adopted by Gaines & Hipskind, 1998.
A Fortran programme to write NASA Ames file headers is available from the BADC.

Important general rules

All independent variables must be monotonic (i.e. their values must be ordered by strictly increasing or decreasing order). The word strictly in the brackets ensures that dependent variables are functions of the independent variable(s). A particular implication of this requirement is that any independent variable cannot be set to the same value more than once within a single span of its domain. This rule also applies when the variable is a character string (case of X2 in FFI 2160), the order here being the alphanumeric order.
For all FFIs, primary variables are real.

Remark

For all FFIs pertaining to data records including auxiliary variables (i.e. all except 1001), the auxiliary variables solely depend on the last (i.e. the most slowly varying) independent variable, which is also the (only) unbounded** independent variable.

Table 1. NASA Ames data file structure.

Section Content Format

Metadata
(header) Top seven lines Information about the experiment Common to all FFIs

Body Information about the data See link in Table 2 below

Tail Comments Common to all FFIs

Data Data See link in Table 2 below

Section	Content	Format
Metadata (header)	Top seven lines	Information about the experiment	Common to all FFIs
Body	Information about the data	See link in Table 2 below
Tail	Comments	Common to all FFIs
Data	Data	See link in Table 2 below

Table 2. Definition of File Format Indices.
N.B. (1) Independent variable values must be ordered so as to be strictly increasing or decreasing. (2) For all FFIs, primary variables are real. (3) For all FFIs pertaining to data records including auxiliary variables (i.e. all except 1001), the auxiliary variables solely depend on the last (i.e. the most slowly varying) independent variable, which is also the (only) unbounded** independent variable.

Number of independent variables	1			2				3	4
FF Index	1001	1010	1020	2010	2110	2160	2310	3010	4010
Independent variables characteristics	Unbounded**	Unbounded**	Unbounded** with uniform increment Partly implicit: only a subset of regularly spaced marks is recorded.*	1 real bounded & 1 real unbounded Both variables are given on a fixed grid.	1 real bounded & 1 real unbounded The set of values taken by the bounded variable depends on the unbounded variable values.	1 real bounded & 1 unbounded character string The set of values taken by the bounded variable depends on the unbounded variable values.	1 real bounded & 1 real unbounded At each unbounded variable mark, the values of the bounded variable are regularly spaced, but they depend on the unbounded variable value.	2 bounded & 1 unbounded	3 bounded & 1 unbounded
Auxiliary variables characteristics	No auxiliary variable	Real	Real	Real	The 1^st auxiliary variable is the number (integer) of values of the bounded** independent variable. Other auxiliary variables are real.	The 1^st auxiliary variable is the number (integer) of values of the bounded** independent variable. The next auxiliary variables are real. The last auxiliary variables may be character strings.	The first 3 auxiliary variables are the number of values of the bounded variable (integer), its base value (real) and the value of its (regular) increment (real). Other auxiliary variables are real.	Real	Real
Data format	Please click	Please click	Please click	Please click	Please click	Please click	Please click	Please click	Please click
Metadata format	Please click	Please click	Please click	Please click	Please click	Please click	Please click	Please click	Please click
Examples	Please click	Please click	Please click	Please click	Please click	Please click	Please click	Please click	Please click
FF Index	1001	1010	1020	2010	2110	2160	2310	3010	4010

* Implicit denotes a variable of which the values are not recorded in the data file, but are deductible from the information provided in the data file header. Explicit applies to a variable of which all the values are explicitly recorded in the data file. A variable can be partly implicit (as in FFI 1020) if only a subset of its values is recorded.

** In this particular context, a variable is said to be bounded if the number of its values is explicit*. If this number is implicit*, the variable is unbounded.

Table 3. Summary of metadata format (header) for all FFIs.

1001 1010 1020 2010 3010 4010 2110 2310 2160

Top NLHEAD FFI
ONAME
ORG
SNAME
MNAME
IVOL NVOL
DATE RDATE

Body [ DX^s s=1,NIV ] DX^NIV DX¹

NVPM [ NX^s s=1,NIV-1 ]
[ NXDEF^s s=1,NIV-1 ]
[ X^s(i) i=1,NXDEF^s ] s=1, NIV-1 LENX

[ XNAME^s ] s=1,NIV
NV
[ VSCAL_n n=1,NV ]
[ VMISS_n n=1,NV ]
[ VNAME_n ] n=1,NV

NAUXV

[ ASCAL_a a=1,NAUXV ]
[ AMISS_a a=1,NAUXV ]
NAUXC
[ ASCAL_a a=1,NAUXV-NAUXC ]
[ AMISS_a a=1,NAUXV-NAUXC ]
[ LENA_a a=NAUXV-NAUXC+1,NAUXV ]
[ AMISS_a ] a=NAUXV-NAUXC+1,NAUXV

[ ANAME_a ] a=1,NAUXV

Tail NSCOML
[ SCOM_k ] k=1,NSCOML
NNCOML
[ NCOM_k ] k=1,NNCOML

1001 1010 1020 2010 3010 4010 2110 2310 2160