Machine-readable Options and Cost 3. The meta-data header provides the key to interpreting the data that follows. Most of the common astronomical units have predefined symbols . Note that the standard is to use SI units. Some of the most common astronomical values have predefined labels .
Data columns that reference other columns also have predefined labels .
The description can also be preceded by other characters which have special meaning. The values between the brackets are the only allowed values that may appear in the data column. All other values are flagged in the data checking program.