-DC Lines in a Database Block

The -DC Lines tab is dedicated to the description of the CODASYL, DMSII, and TANDEM Database Blocks. You can declare the areas, call the records, and distribute them within the AREAS, call the SETS and describe them (name, label, parent, and child Segments).

This description is common to the following Block types:

-DC Lines definition

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,

TANDEM database

R Record.
Database object name
In this field, you enter the code which corresponds to the selected description line type.
  • Type S: Set code, on five characters
  • Type A: Area code, on five characters
  • Type R: Code of the area to which the record belongs.
Segment
This field cannot be used if the type of line is A (Area). Select the parent Segment or record depending on the type of description line selected.
  • CODASYL database:
    • If the type is R, you select the record code.
    • If the type is S, you indicate the parent Segment code.
  • TANDEM database:

    You enter the Segment code which corresponds to the called record. When the Database Block is generated, this code is displayed after the RECORD clause.

    To modify the contents of this field, click Change. Then select a Segment. If the list is large, you can reduce it by entering a string that is used as a filter (the filtering is performed on the code or on the label of the instance).

Child Segment
This field can be used with an S-type line only. Select the child Segment code (member) by clicking the Change button, as for the Segment code.
From Segment
This field is active only for an R-type line (Record). In this field, you must enter the name of the physical file (file name), which supports the data. When the Database Block is generated, this name is displayed after the FILE IS clause.
Method name
Schema:

This field can be used with an S-type line only.

Subschema:

Only used for IDMS (D3, D4 types), DM4 (M3 type) and DMS (S3 type) subschemas.

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
CODASYL database:

Depending on the value of the Type of line selected, you enter:

  • The name of the Set (S-type line),
  • The name of the Area (A-type line),
  • A comment (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 (with n being 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.

TANDEM database:

You enter the name of the physical file which supports the data. When the Database Block is generated, this name is displayed after the FILE IS clause.

-G Lines
This button can be used to access the -G Lines wizard and create -GG lines associated with the description line to specify generation elements.

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