Control File: invalid character for a field name

Field names (and as a side effect variasble names) must be composed of only the following characters:

• A-Z — upper case letters
• a-z — lower case letters
• 0-9 — digits
• _ — underscore
• + — plus character (forbidden as the first character)
• - — minus or dash character (forbidden as the first character)
• . — period (forbidden as the first character)

The field can also include a slash (/) character, in which case there is a Sub-Package name included. The same restrictions apply to the Sub-Package name as to the Field name. No more than one slash (/) character can be included or an error is generated.