Creating a solution > Defining database fields > About naming fields
About naming fields
Field names must be unique within a table. Follow these guidelines when naming fields:
Do not use any of the following symbols and words in the field name:
,(comma), +, -, *, /, ^, &, =, , >, <, ( ), [ ], { }, ", ; (semicolon), : (colon), :: (relational indicator), $ (variable indicator)
AND, OR, NOT, XOR, TRUE, FALSE, or the name of any FileMaker Pro function
Don't begin a field name to be used in a calculation formula with a space, period (.), or number.
Use _ (underscore) in place of a space to avoid restrictions in ODBC, exporting, web publishing, and other operations.
If you're exchanging data with another application, check the field naming restrictions in the file formats supported by that application.
If you're using ODBC or JDBC to share FileMaker Pro data, avoid using SQL keywords in field names.
Related topics 
Using a reserved word or symbol for a field or table name