-DC Lines in a Database Block

In the -DC Lines tab, you declare the areas, call the records, and distribute them within the areas, call the sets and describe them. You specify this information directly in the table or in the call line definition section that opens when you create a line or select a line in the table.

This description is common to the following Block types:
  • CODASYL-DM4:
    • M1: DM4 DDL schema (only elementary fields are generated)
    • M4: DM4 DDL schema (only group fields are generated)
    • M2: DM4 DMCL schema
    • M3: DM4 subschema
    Note: A schema or subschema is comparable to a Database Block.
  • CODASYL-IDS2:
    • I1: IDS2 DDL schema
    • I2: IDS2 DMCL schema
    • I3: IDS2 SDDL subschema
  • CODASYL-IDMS:
    • D0: IDMS DDL schema
    • D2: IDMS DMCL schema
    • D4: IDMS subschema
  • DMSII database:
    • 20: DMSII
  • CODASYL-DMS:
    • S1: DMS schema
    • S3: DMS subschema
  • TANDEM:
    • TD: TANDEM

The Comments column is displayed in the table only. It does not correspond to a field of the call line definition section. It contains an asterisk on the call lines that have been assigned -G lines. These secondary-level -G lines were entered with the -G Lines button in the call line definition section. If you hover your cursor on the asterisk, the -G lines of the call line are displayed in a tooltip. If you click the button that is associated with the asterisk, the -G lines are displayed in their tabular editor, where you can modify them. You can also display and modify the -G lines from the Edit comments choice in the contextual menu of the call line.

-DC Line Definition section

The following explanations refer to the fields as they are displayed in the call line definition section.
Network record type
Select a type of line among the authorized values.
Table 1. Type of line
Value Description
* Continuation of a set. For a set with multiple members, the first member Segment is indicated on an S-type line and the other Segments on *-type lines.
S Set (default option).
A Area for TANDEM database.
R Record.
Database object name
Enter the name that corresponds to the selected description line type.
  • On a type S, enter the set code on 5 characters.
  • On a type A, enter the area code on 5 characters.
  • On a type R, enter the code of the area that the record belongs to.
Segment
This field cannot be used if the type of line is A (area). Select the parent Segment or record, depending on the selected description line type.

For a CODASYL database, if the type is R, you select the record code. If the type is S, you indicate the parent Segment.

For TANDEM database, you enter the Segment that corresponds to the called record. When the Database Block is generated, the Segment is displayed after the RECORD clause.

To enter or modify the contents of this field, click Change. In the dialog box that opens, select a Segment in the list and click OK. It is then displayed in the Segment column.

You can specify the Segment directly from the Segment column.

Two methods are possible:
  • Place the cursor in the column and enter the name directly. To make the input easier, you can open a content assist wizard by clicking Ctrl and the space bar simultaneously. If you start entering a name, the content assist displays the instances that start with this input. If you enter the name of an instance that does not exist and if you validate, the input is discarded.
  • Click the button that appears when you set your cursor in the column. In the selection wizard that opens, select an instance.
Child Segment
This field can be used with an S-type line only. It contains the child Segment ("MEMBER").

To enter or modify the contents of this field, click Change. In the dialog box that opens, select a Segment in the list and click OK. It is then displayed in the Child column.

You can specify the Segment directly from the Child column.

Two methods are possible:
  • Place the cursor in the column and enter the name directly. To make the input easier, you can open a content assist wizard by clicking Ctrl and the space bar simultaneously. If you start entering a name, the content assist displays the instances that start with this input. If you enter the name of an instance that does not exist and if you validate, the input is discarded.
  • Click the button that appears when you set your cursor in the column. In the selection wizard that opens, select an instance.
From Segment
This field is active only for an R-type line (Record). In this field, you enter the name of the physical file (file name) that contains the data. When the Database Block is generated, this name is displayed after the FILE IS clause.

To enter or modify the contents of this field, click Change. In the dialog box that opens, select a Segment in the list and click OK. It is then displayed in the From Seg column.

You can also specify the Segment directly from the From Seg column.

Two methods are possible:
  • Place the cursor in the column and enter the name directly. To make the input easier, you can open a content assist wizard by clicking Ctrl and the space bar simultaneously. If you start entering a name, the content assist displays the instances that start with this input. If you enter the name of an instance that does not exist and if you validate, the input is discarded.
  • Click the button that appears when you set your cursor in the column. In the selection wizard that opens, select an instance.
Method name
For a schema, this field can be used with an S-type line only.
For a subschema, this field can be used only for IDMS (D3, D4 types), DM4 (M3 type), and DMS (S3 type).

On an R-type line, you can change the description of the selected record.

Number of Occurrences of sets
This field can be used with an S-type line only. You enter the average number of occurrences of the child Segment that are linked to an occurrence of the parent Segment. This number is used for the activity calculation.
Area name, Set name or comment
For a CODASYL database, you enter the following elements, according to the line Type:
  • The name of the set on a S-type line
  • The name of the area on an A-type line
  • A comment on an R-type line

For an IDMS (D4) or DMS (S3) subschema, you can select a subschema at the Block description level. To do so, on R-type lines, enter SS=n (where n is the subschema number according to the definition).

For an IDS2 (I3) subschema, it is possible to call an object (area, record, set) without redescribing it, by specifying INCLUSION.

For a TANDEM database, you enter the name of the physical file that contains the resources. When the Database Block is generated, this name is displayed after the FILE IS clause.

-G Lines
Click this button to access the -G Lines wizard and associate -GG lines with the description line to specify generation elements.

Feedback