A position along a dimension can be specified using an index . This is an integer with a minimum value of 0 for C programs. Thus the 700 millibar level would have an index value of 2 in the example above. If a dimension has a corresponding coordinate variable, then this provides an alternative, and often more convenient, means of specifying position along it. Most attributes provide information about a specific variable.
Some attributes provide information about the dataset as a whole and are called global attributes.
Conventional attribute names should be used where applicable. New names should be as meaningful as possible. The external type of an attribute is specified when it is created. The types permitted for attributes are the same as the netCDF external data types for variables. Attributes with the same name for different variables should sometimes be of different types.