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This document covers the following topics:

• Function and Use

• Control Block

• Record Buffer for Command Option 2 = 'S'

• Record Buffer for Command Option 2 = Blank

• Record Buffer for Command Option 2 = ‘X’ and ‘F’

• Example

Function and Use

The LF command is used to read the field definition information for a file.

The user specifies the file number for which the field definitions are to be returned.

Adabas returns the field definition information in the record buffer. The following information is returned for each field:

• Level number;

• Name;

• Standard length;

• Standard format;

• Definition options.

This command can be used to obtain the standard field length and format of a field during program execution in order to dynamically create a format or search buffer.

The timestamp when the field definitions were last updated is returned in the record buffer when the command option 2 = ‘X’. This may be one of the following:

• The time when the file was created;

• The time when a field was last added, changed or deleted;

• A descriptor was last inverted or released.

If a file is imported with ADAORD or restored with ADABCK, the timestamp of the import or restore is not stored; the original timestamp of the file when it was exported or dumped is kept.

Note:
The LF command only reads meta information on the file, but not the file itself. For this reason, an LF command can also be performed on a file that is currently exclusively locked by an application program or which is locked by a utility.

LF Command, Procedure Flow

Control Block

Buffer Areas

Formats:

A	alphanumeric
B	binary

x/y before/after Adabas call - x and y can take the values:

A	Filled in by Adabas
F	To be filled in by User
U	Unchanged after Adabas call
-	Not used
*	Not used but must be included in parameter list of CALL statement

(1) The meaning of this field depends on the value specified for "Call Type". See Calling Adabas, The Control Block for details.

Control Block

Command Code

LF

File Number

The number of the file for which the field definition information is to be returned.

Response Code

Adabas returns the response code for the command in this field. Response code 0 indicates that the command was executed successfully.

Record Buffer Length (ACB only)

The record buffer length (in bytes). The length specified must be large enough to contain all field definition information for the file and must not be greater than the size of the record buffer area defined in the user program.

Command Option 2

The setting of this field determines the format and type of information to be returned in the record buffer.

An ‘S’ in this field returns the standard information on the file that was available already with Adabas Version 6.1. However, this information is not complete; in particular, the new features introduced with Adabas Version 6.2 are not supported.

An ‘X’ in this field returns extended information on the file in the record buffer. This contains all information required to create a file with the same FDT.

An ‘F’ in this field returns full information on the FDT. It is similar to the ‘X’ option but with the difference that logically-deleted fields are also returned in the record buffer.

Notes:

1. You can only load data with the ADAMUP utility if the FDT of the decompressed data is the same as the FDT of the target file, including the logically-deleted fields.
2. Logically-deleted fields are returned in the record buffer without field names.

A blank in this field returns only the basic information on the fields of the file; only a subset of the options is returned. No information on special descriptors is returned.

Additions 2

Adabas returns the total length of the returned structure in this field.

For some response codes, Adabas returns detailed information in this field. See Adabas Messages And Codes for further information.

Additions 3

This field is used to provide a security password.

If the file to be used is not security protected, this field should be set to blanks. If the file is security protected, the user must provide a valid password.

Adabas sets this field to blanks during command processing to protect the integrity of any password provided.

Record Buffer for Command Option 2 = 'S'

All field definition information is returned in the record buffer.

Setting the Command Option 2 field to `S' returns the information in the following format:

Record Buffer General Layout

FDT Field Definitions

Warning: In order to be mainframe-compatible, the bit for the NV option has been changed: in Adabas Version 3.3 and earlier, NV option = 0x04; in Adabas Version 5.1 and higher and Adabas on mainframes, NV option = 0x40.

SDT Field Definitions

Collation Descriptor Definitions

Hyperdescriptor Definitions

Phonetic Descriptor Definition

Subdescriptor Definition

Superdescriptor Definition

For the second and subsequent parent fields, the following table applies:

Record Buffer for Command Option 2 = Blank

Information for all fields of a file, but not for special descriptors (for example, superdescriptors), is returned in the record buffer, Setting the command option 2 to blank returns the information in the following format:

Record Buffer General Layout

FDT Field Definitions

Note:
The definition options in the record buffer for command option 2 = blank are not mainframe-compatible. Mainframe-compatible LF commands are only possible with command option 2 = S.

Record Buffer for Command Option 2 = ‘X’ and ‘F’

Setting command option 2 to ‘X’ or ‘F’returns the information in the following format:

Record Buffer General Layout

Notes:

• Each entry in the record buffer begins with the following fields:

  • Byte 1: Type of the entry

  • Byte 2: Length of the entry

  • Byte 3-4: Name of the entry

  • Byte 5: Format (Not for RI constraints)

  • Byte 6: Options (Not for RI constraints)

  • Descriptor length (Only for SDT entries)

• In order to be compatible with future Adabas versions, please consider the following:

  • Future Adabas versions may provide additional entry types for the ‘X’ option, therefore, you should not consider unknown entry types to be an error.

  • The record buffer entries may be larger than with the current Adabas version. Therefore, you should always use the entry length field to skip to the next entry. The information currently returned in the record buffer will also be returned at the same position in a record buffer entry with future Adabas versions.

  • The length of each entry is aligned to 4 bytes so that you can access 4-byte integer values without alignment problems.

• There may be more entries returned in the LF command than specified in the file definition, because the names of referential integrity constraints are defined only for the file containing the foreign key, but they are also re-turned by the LF command for the file containing the primary key.

FDT Field Definitions

SDT Field Definitions

There are SDT field definitions for the same descriptor types and with the same first byte as for the ‘S’ option.

Collation Descriptor Definitions

Notes:

1. The C entry length is aligned to 4 bytes.
2. The format of parent field is relevant if you specify a parent field value in the value buffer. If the collation descriptor is defined without the HE option, you can also specify the internal collation descriptor values. These values have the format A with the option NV.

Hyperdescriptor Definitions

Note:
The H entry length is aligned to 4 bytes.

Phonetic Descriptor Definitions

Sub-/Superdescriptor Definitions

Note:
The sub-/superdescriptor entry length is aligned to 4 bytes.

Referential Integrity Definitions

The FDTs of each of the two referenced files contain an entry for a referential constraint. If both the foreign and primary key are in the same file for a referential constraint, the FDT of this file contains two entries for this constraint.

Note:
The name of a referential integrity constraint may also occur as the name of a field or special descriptor of the file.

Example

The field definition information (including features introduced with Adabas version 6.2) for file 1 is to be read.

Control Block:

Command Code          LF

File Number           1 (field definitions for file 1 requested)

Record Buffer Length  100

Command Option 2      X

Additions 3           bbbbbbbb (file is not security protected)

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