Column headings should be meaningful, but not overly long. Use only alphanumeric characters or hyphens in column headings.
When using non-standard codes, create a supplemental table with code definitions to define the codes in the metadata.
If the data file is in a comma-separated value (CSV), avoid using special characters, such as commas, semicolons, or tabs.
Use only the first row to identify a column heading. Examples of good column headings:
Present date information in an appropriate machine-readable format.
For example yyyymmdd or yyyy-mm-dd.
Indicate the time zone and the use of a 12-hour or 24-hour system. Other example includes mm: two-digit minutes; ss: two-digit seconds; TZD: time zone designator.