All CF attributes are listed here except for those that are used to describe grid mappings. See Appendix F for the grid mapping attributes.
The "Type" values are S for string, N for numeric, and D for the type of the data variable. The "Use" values are G for global, C for variables containing coordinate data, and D for variables containing non-coordinate data. "Links" indicates the location of the attribute"s original definition (first link) and sections where the attribute is discussed in this document (additional links as necessary).
Table A.1. Attributes
| Attribute | Type | Use | Links | Description |
|---|---|---|---|---|
actual_range | N | C, D | Section 2.5.1, “Missing Data, valid and actual range” | The smallest and the largest valid non-missing values occurring in the variable |
add_offset | N | D | NUG (8.1) NUG (8.1) , Section 8.1, “Packed Data” | If present for a variable, this number is to be added to
the data after it is read by an application. If both
scale_factor and add_offset
attributes are present, the data are first scaled before the
offset is added. |
ancillary_variables | S | D | Section 3.4, “Ancillary Data” | Identifies a variable that contains closely associated data, e.g., the measurement uncertainties of instrument data. |
axis | S | C | Chapter 4, Coordinate Types | Identifies latitude, longitude, vertical, or time axes. |
bounds | S | C | Section 7.1, “Cell Boundaries” | Identifies a boundary variable. |
calendar | S | C | Section 4.4.1, “Calendar” | Calendar used for encoding time axes. |
cell_measures | S | D | Section 7.2, “Cell Measures” | Identifies variables that contain cell areas or volumes. |
cell_methods | S | D | Section 7.3, “Cell Methods”, Section 7.4, “Climatological Statistics” | Records the method used to derive data that represents cell values. |
cf_role | C | C | Section 9.5, “Coordinates and metadata” | Identifies the roles of variables that identify features in discrete sampling geometries |
climatology | S | C | Section 7.4, “Climatological Statistics” | Identifies a climatology variable. |
comment | S | G, D | Section 2.6.2, “Description of file contents” | Miscellaneous information about the data or methods used to produce it. |
compress | S | C | Section 8.2, “Compression by Gathering”, Section 5.3, “Reduced Horizontal Grid” | Records dimensions which have been compressed by gathering. |
Conventions | S | G | NUG (8.1) NUG (8.1) | Name of the conventions followed by the dataset. |
coordinates | S | D | Chapter 5, Coordinate Systems, Section 6.1, “Labels”, Section 6.2, “Alternative Coordinates” | Identifies auxiliary coordinate variables, label variables, and alternate coordinate variables. |
_FillValue | D | C, D | NUG (8.1) NUG (8.1) | A value used to represent missing or undefined data. Not allowed for coordinate data except in the case of auxiliary coordinate varibles in discrete sampling geometries. |
featureType | C | G | Section 9.4, “The featureType attribute” | Specifies the type of discrete sampling geometry to which the data in the file belongs, and implies that all data variables in the file contain collections of features of that type. |
flag_masks | D | D | Section 3.5, “Flags” | Provides a list of bit fields expressing Boolean or enumerated flags. |
flag_meanings | S | D | Section 3.5, “Flags” | Use in conjunction with flag_values to
provide descriptive words or phrases for each flag value. If
multi-word phrases are used to describe the flag values, then the
words within a phrase should be connected with
underscores. |
flag_values | D | D | Section 3.5, “Flags” | Provides a list of the flag values. Use in conjunction with
flag_meanings. |
formula_terms | S | C | Section 4.3.2, “Dimensionless Vertical Coordinate” | Identifies variables that correspond to the terms in a formula. |
grid_mapping | S | D | Section 5.6, “Grid Mappings and ProjectionsHorizontal Coordinate Reference Systems, Grid Mappings, and Projections” | Identifies a variable that defines a grid mapping. |
history | S | G | NUG (8.1) NUG (8.1) | List of the applications that have modified the original data. |
instance_dimension | N | D | Section 9.3, “Representations of collections of features in data variables” | An attribute which identifies an index variable and names the instance dimension to which it applies. The index variable indicates that the indexed ragged array representation is being used for a collection of features. |
institution | S | G, D | Section 2.6.2, “Description of file contents” | Where the original data was produced. |
leap_month | N | C | Section 4.4.1, “Calendar” | Specifies which month is lengthened by a day in leap years for a user defined calendar. |
leap_year | N | C | Section 4.4.1, “Calendar” | Provides an example of a leap year for a user defined calendar. It is assumed that all years that differ from this year by a multiple of four are also leap years. |
long_name | S | C, D | NUG (8.1) NUG (8.1) , Section 3.2, “Long Name” | A descriptive name that indicates a variable"s content. This name is not standardized. |
missing_value | D | C, D | Section 2.5.1, “Missing Data, valid and actual range” | A value used to represent missing or undefined data (deprecated by the NUG). Not allowed for coordinate data except in the case of auxiliary coordinate variables in discrete sampling geometries. |
month_lengths | N | C | Section 4.4.1, “Calendar” | Specifies the length of each month in a non-leap year for a user defined calendar. |
positive | S | C | [COARDS] | Direction of increasing vertical coordinate value. |
references | S | G, D | Section 2.6.2, “Description of file contents” | References that describe the data or methods used to produce it. |
sample_dimension | N | D | Section 9.3, “Representations of collections of features in data variables” | An attribute which identifies a count variable and names the sample dimension to which it applies. The count variable indicates that the contiguous ragged array representation is being used for a collection of features. |
scale_factor | N | D | NUG (8.1) NUG (8.1) , Section 8.1, “Packed Data” | If present for a variable, the data are to be multiplied by
this factor after the data are read by an application See also the
add_offset attribute. |
source | S | G, D | Section 2.6.2, “Description of file contents” | Method of production of the original data. |
standard_error_multiplier | N | D | Appendix C, Standard Name Modifiers | If a data variable with a standard_name modifier of standard_error has this attribute, it indicates that the values are the stated multiple of one standard error. |
standard_name | S | C, D | Section 3.3, “Standard Name” | A standard name that references a description of a variable"s content in the standard name table. |
title | S | G | NUG (8.1) NUG (8.1) | Short description of the file contents. |
units | S | C, D | NUG (8.1) NUG (8.1) , Section 3.1, “Units” | Units of a variable"s content. |
valid_max | N | C, D | NUG (8.1) NUG (8.1) | Largest valid value of a variable. |
valid_min | N | C, D | NUG (8.1) NUG (8.1) | Smallest valid value of a variable. |
valid_range | N | C, D | NUG (8.1) NUG (8.1) | Smallest and largest valid values of a variable. |