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 Passwords and Security
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     Although the Paradox DBMS cannot be considered a data dictionary system,
     it does have some special characteristics that make it more suitable to
     networks than the standard Xbase tables.  One of these features is the
     level of security available.

     There are two methods to make sure that your data is secure: master
     passwords and auxiliary passwords.  As the owner of a table, you can
     limit access by attaching a master password to it.  Auxiliary passwords
     can also be identified to establish access to the table and its family.

     Once any type of password is identified for a table, its is encrypted.
     This protects it not only from unauthorized Paradox users but also from
     anyone trying to dissect it at the DOS file level.  The encryption
     method used by Paradox is literally unbreakable and if you (or your
     users) forget a table password, there is no way to recover that
     information.

     Auxiliary passwords allow access control at the table and field levels.
     Access to tables can be restricted to:

     .  ReadOnly:  No changes to the table can be made

     .  Update:  Changes to nonkey fields are allowed, no records can
        be added or deleted

     .  Entry:  Same as update except that new records can be added

     .  InsertDelete:  Same as Entry except that records can be
        inserted and deleted

     .  All:  Full access including restructuring and table deletion

     Access to the fields can be identified as:

     .  None:  This field data cannot be displayed to the user

     .  ReadOnly:  User can see the field value, but cannot change it

     .  All:  Full access

     With DBPX, you may perform basic database operations on Paradox tables
     without code changes.

     Note that because Paradox tables can have primary indexes which are
     actually part of the table structure specification, when you open a
     Paradox table, its associated primary index (if applicable) is also
     opened and activated.  The only exception to this rule is if you
     indicate that you want a secondary index to be activated at the time you
     open the table.  If no primary index is available and no secondary index
     is specified, the table is opened in natural sequence order.

     You can have up to twenty-four Paradox tables open simultaneously.
     These may be separate tables or the same table repeatedly or any
     variation in between.  This might be important if you want to have more
     than one secondary index active for a single table, allowing you to move
     from one work area to another with the only change being the index order
     of the data in the table.  Be careful with this type of multiviewed
     approach, however, since you will be eating up memory for each work
     area, despite the fact that they refer to the same table.

 Sharing Data in Networks

     The DBPX driver supports the native CA-Clipper  single-lock locking
     scheme.  Therefore, in a shared environment, your application and
     Paradox will not see each other's record locks.  This may result in some
     concurrency corruption and errors.

     In a shared environment, DBPX performs no record buffering; immediately
     writing all changes to disk.

     Concurrency is an issue whenever your application is running either on a
     network or in some other shared environment.  One example of a non-
     network shared environment is when your application is called from
     another program (like Paradox, Quatro Pro, etc.) that also has access to
     the Paradox tables.  Even if you don't have any plans to use your
     program on a network, you should design it to be smart enough not to
     become a problem if faced with this type of shared example.

     Also be aware that many networks have different rights and privilege
     restrictions and you should know what they are and how to handle them.