FAB

   The file access block (FAB) defines file characteristics, file
   access, and certain run-time options. It also indicates whether
   other control blocks are associated with the file.

   The following table lists the symbolic offset, the size in bytes,
   the FDL equivalent, and a brief description of each FAB field.

   Field Offset   Size  FDL Equivalent          Description

   FAB$B_         1     None                    File access modes
   ACMODES
   FAB$L_ALQ      4     FILE ALLOCATION         Allocation quantity
                                                (blocks)
   FAB$B_BID      1     None                    Block identifier
   FAB$B_BKS      1     FILE BUCKET_SIZE        Bucket size
   FAB$B_BLN      1     None                    Block length
   FAB$W_BLS      2     FILE MT_BLOCK_SIZE      Magnetic tape block
                                                size
   FAB$V_CHAN_    -     None                    Channel access mode
   MODE                                         protection
   FAB$L_CTX      4     FILE CONTEXT            Context
   FAB$W_DEQ      2     FILE EXTENSION          Default file
                                                extension quantity
   FAB$L_DEV      4     None                    Device
                                                characteristics
   FAB$L_DNA      4     FILE DEFAULT_NAME       Default file
                                                specification string
                                                address
   FAB$B_DNS      1     FILE DEFAULT_NAME       Default file
                                                specification string
                                                size
   FAB$B_FAC      1     ACCESS                  File access
   FAB$L_FNA      4     FILE NAME               File specification
                                                string address
   FAB$B_FNS      1     FILE NAME               File specification
                                                string size
   FAB$L_FOP      4     FILE                    File-processing
                                                options
   FAB$B_FSZ      1     RECORD CONTROL_FIELD_   Fixed-length control
                        SIZE                    area size
   FAB$W_GBC      2     FILE GLOBAL_BUFFER_     Global buffer count
                        COUNT
   FAB$W_IFI      2     None                    Internal file
                                                identifier
   FAB$B_         1     None                    Journal flags status
   JOURNAL
   FAB$V_LNM_     -     None                    Logical name
   MODE                                         translation access
                                                mode
   FAB$L_MRN      4     FILE MAX_RECORD_        Maximum record
                        NUMBER                  number
   FAB$W_MRS      2     RECORD SIZE             Maximum record size
   FAB$L_NAM      4     None                    Name (NAM) or long
                                                name (NAML) block
                                                address
   FAB$B_ORG      1     FILE ORGANIZATION       File organization
   FAB$B_RAT      1     RECORD                  Record attributes
   FAB$B_RFM      1     RECORD FORMAT           Record format
   FAB$B_RTV      1     FILE WINDOW_SIZE        Retrieval window
                                                size
   FAB$L_SDC      4     None                    Secondary device
                                                characteristics
   FAB$B_SHR      1     SHARING                 File sharing
   FAB$L_STS      4     None                    Completion status
                                                code
   FAB$L_STV      4     None                    Status values
   FAB$L_XAB      4     None                    Extended attribute
                                                block address