Limitation on object names

[MaartenSneepKNMI]

Note: This remark was originally part of issue #4. Split of to separate the discussions.

Use case

In issue #4 references between variables are discussed. These occur in space separated lists, and as such they put a limitation on the allowable characters in object names.

The problem

NetCDF-4 allows an object name like "χ²" (\u03C7\u00B2). This is probably very good for human readability, but accessing the field from a program or script (non-interactively) is probably pretty hard.

To get the string into this text file I went into an interactive python3 shell, and asked it to print("\u03C7\u00B2"), and those numbers were obtained from a website. Other computer systems may offer more convenient access.

Terminology

For some of the terminology refer to “CDM Object Names” and the discussion summary of issue #4.

In particular, an “object name” refers to the short name of either a group, variable, dimension, attribute, type definition or field in a compound datatype.

Suggested solution

The short names of NetCDF-4 objects must match the regular expression: [a-zA-Z_][a-zA-Z0-9_]*. This means that the name of a NetCDF-4 object can be used as a variable name in most programming languages.

If there is a need to attach a name to a variable that requires the use of other characters, then an attributes can be used. A possible solution for this would be an attribute with the name “local_name_zh_CN” for a Chinese localisation. The end of the attribute name follows ISO 639-1/ISO 639-2.

Now all we need is a code for “mathematical localisation”.

[dblodgett-usgs]

@MaartenSneepKNMI -- should we migrate this issue to the main repository or has it been taken care of?