To be able to open tables and to access their data from a DataFlex program, we need to know how the table is structured; which fields are defined and what their type and length are; what indexes are defined (consisting of which segments) and so forth.
We retrieve most of the structural information from the database (in the case of Pervasive.SQL, the meta database: the FILE.DDF, FIELD.DDF and INDEX.DDF tables). Not all of that information is available for all target database formats. For example, the concept of a DataFlex system table (a table with 1 record that is automatically read when the table is opened) is unknown outside of the Embedded Database. So, the information that a certain table is a system table must be stored somewhere else.
The intermediate (.INT) file is the location where this type of information is stored. The contents of an intermediate file can be divided into three sections.
A section that allows DataFlex to determine which database driver to use
A section that contains information needed before a table can be opened
A section that contains information needed after a table has been opened
The general format of the intermediate file consists of lines of text separated by carriage return and line feed (CR/LF) characters. Each line may be up to 255 characters long and consists of a keyword and value pair or a comment.
Keywords may be upper, lower or mixed case. Comments are preceded by the semicolon (;) character. In line comments are not supported. White space, defined as blank spaces and tab characters, is not significant and may be used for legibility.
The specific meaning and usage of intermediate file keywords are entirely dependent upon the specific database driver with the exception of the DRIVER_NAME keyword.
In general, an intermediate file must be present for every table that is accessed through the driver. In some specific circumstances an intermediate file can be omitted.
Intermediate files are automatically created when converting data or when connecting to existing data using one of the connect wizards. When restructuring existing tables with Database Builder, intermediate files will be updated if necessary. Intermediate files will also be updated as necessary when executing any code that causes a table to restructure (e.g. a structure_start...structure_end code block). It is also possible to create or edit intermediate files manually with a text editor.
Understanding How Connectivity Works