The input (.vdi) and output (.vdo) files have the same structure. Each file is a plain text file made up a series of keywords, which begin with a colon :, followed by values. Some of these are informational and are used to prepare queries and add selection clauses, and some are action keywords which are used to take an action. The informational keywords relating to an action must precede the action. Most informational keywords set values that are cleared after each action is performed, though a few of them are persistent.
Many keywords will be followed by the name of a field in the database being accessed. The field will be used to read information from or write information to the database. It is best to use field names that do not have any embedded spaces or special characters. If you do have special characters or embedded spaces you can try putting double quotes " around the field name though this may not work with all ODBC sources.
Sometimes, rather than querying the database for the value of a field you may want to specify a literal value. In this case prefix the value with a sharp sign # (this is also called a pound sign and a hash sign). What follows will be treated as if it were the result of a query from the database but the database will not be referenced for that value. See the examples section below.
