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 |
|---|---|---|---|---|
add_offset | N | D | 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. |
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) | 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 | D | NUG (8.1) | A value used to represent missing or undefined data. |
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) | List of the applications that have modified the original data. |
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), Section 3.2, “Long Name” | A descriptive name that indicates a variable"s content. This name is not standardized. |
missing_value | D | D | Section 2.5.1, “Missing Data” | A value used to represent missing or undefined data (deprecated by the NUG). |
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. |
scale_factor | N | D | 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) | Short description of the file contents. |
units | S | C, D | NUG (8.1), Section 3.1, “Units” | Units of a variable"s content. |
valid_max | N | C, D | NUG (8.1) | Largest valid value of a variable. |
valid_min | N | C, D | NUG (8.1) | Smallest valid value of a variable. |
valid_range | N | C, D | NUG (8.1) | Smallest and largest valid values of a variable. |