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This document covers the following topics:

• Field List Tab

• Field Type

• Level Number

• Field Format

• Character Set

• Character Set - Adabas

• Field Length

• Descriptor Type

• Descriptor Type - continued

• Maximum Number of Values / Occurrences

• Unique Option

• Field Short Name

• Suppression / Null Value Option

• Variable Length Option - IMS

• Null Default Option

• Natural Field Length

• Do Not Convert Option

• Related Standard File

• Check against standard

• Natural Attributes

• Hidden

Most attributes are applicable to fields of all file types.

Basic attributes applying to different field types are described below. Type-specific attributes are described in the section Defining Derived Fields.

For general information on how to manage objects (for example, how to add or copy an object), see the Predict Object Description documentation.

Field List Tab

Unlike all other predefined object types, a node for the object type Field is not shown at the top level of the tree view window containing the list of all documentation objects.

Fields can only be added via the Field List tab of the object type File.

Fields can be modified in two ways:

• via the Field List tab of the object type File, and

• via the dialog box which appears when you open a field (see Defining Additional Attributes of Fields).

Note:
Field type, level number, field format, field length and the maximum number of values/occurrences can only be modified on the Field List tab since these attributes influence the record structure of a file.

The following information is displayed for fields:

Not all columns of the table on the Field List tab can be shown at the same time. Therefore, a horizontal scroll bar is provided. The columns are described below.

The following commands are available (in addition to the standard commands):

Field Type

The field type is indicated in the column Ty of the Field List tab. The following types can be specified:

Note:
Derived field is also used in Predict as a generic term for hyperdescriptors, phonetic descriptors and sub/superfields and descriptors.

If HM, HP, HQ, HY, OD, PH, SB or SP is specified, an additional window can be invoked using the Source button. See Defining Derived Fields.

Defining Periodic Groups in Periodic Groups

• Within a redefinition, nested periodic groups (PE within a PE) can be defined in files of all types.

• Outside of a redefinition, nested periodic groups can only be defined in files of the following types:

  S	Sequential file
  C	Conceptual file
  M	ISAM file
  Z	Standard file
  O	Other file

Level Number

The level number of the field is indicated in the column L of the Field List tab. The level number is used to define a group structure. Level numbers 1 to 9 can be used (except for Adabas files, see below).

• The level number must be increment by 1 immediately following a field of type RE, PE, PC or GR.

• For redefinitions, the level number must be at least one greater than the level number of the field being redefined.

Adabas Files

The following rules apply to level numbers for Adabas files:

• The PE/PC-groups, sub/superfields/descriptors, hyperdescriptors and phonetic descriptors must be at level 1.

• Level numbers of fields outside a redefinition must be in the range 1 - 7.

Field Format

The format of the field is indicated in the column F of the Field List tab. One of the following values can be specified (depending on the file type):

See tables in the section Field Length for valid combinations of format and length.

The following rules apply:

• Any format/length combination is allowed for the file types C (conceptual) or Z (standard).

• For groups, this attribute must be blank.

• For sub/superfields/descriptors in Adabas files, the appropriate format is provided by Predict based on the formats of the fields used. See Rules Applying to Format Changes.

• The following formats are valid for fields within a redefinition: A, B, D, F, I, L, N/U, NS/US, P, PS, T.

Character Set

The parameter Character set determines the format in which data is stored. It is indicated in column Cs of the Field List tab. The possible values depend on the file type and format.

Note:
A value must be specified for field types and formats marked with an asterisk (*).

Character Set - Adabas

The following character set is used to define wide character fields.

Note:
Option L4 applies to Adabas on Open Systems Version 5 or above only.

Field Length

The field length is indicated in column Length of the Field List tab. This length is independent of its internal representation. When generating external objects, the field length is adjusted according to the internal representation of data used by the data storage system. For example: a field which is documented with length P9 is implemented with length P5 by the Adabas LOADER utility and the Adabas nucleus.

The following additional rules apply:

• For files of type C (conceptual) or Z (standard): Any format/length combination is allowed, and field length zero is permitted for all field formats.

• For groups and phonetic descriptors: Field length must be set to zero.

• For sub/superfields/descriptors in Adabas files: The appropriate length is provided by Predict based on the definition.

• For large object fields: A field length greater than 99999 byte can be defined by entering an additional length unit in the Unit column.

  Valid values:

  blank	bytes
  K	kilobytes
  M	megabytes
  G	gigabytes

  for example, the term 96 implies a field length of 96 bytes while the term 96 M implies a field length of 96 megabytes.

Table of Field Formats and Lengths

The table on the following pages contains the valid format/length combinations for fields of the following file types:

Note:
The tables do not contain the file types C (conceptual) and Z (standard). For these file types, any format/length combinations are allowed.

Key for the following table

Note:
For format LO the length can be specified in units of KB, MB or GB. Enter the desired value followed by the corresponding character (K for KB, M for MB and G for GB). For limitations refer to the above tables.

SQL: DBMS Format and Corresponding Predict Format

The table below indicates the DBMS format and the corresponding Predict format for fields in files of the following types:

Key for the following table

Descriptor Type

The descriptor type is indicated in column D of the Field List tab. The possible values are given in this and the following table.

Additional Information on Descriptor Fields

Descriptor fields can be of various types and control which fields can be used in search criteria (for example in Natural FIND, READ or HISTOGRAM statements). Natural programs can only read Adabas files using fields that are defined as a descriptor (usually type D). It should be part of the design to decide which fields are going to be descriptors, superdescriptors etc.

Adabas however, has a feature where a file can be read using any field - regardless of whether it is a descriptor or not. This is called a non-descriptor search. For large data volumes, this can be very slow. This is because there are no indexes built for non-descriptor fields and a physical scan of the data is required. Despite, if there are only a few records, and it is understood that a physical file scan is taking place, then it can be useful on some occasions.

By putting N into the descriptor type in a DDM, Natural programs are allowed to use this field as a non-descriptor search field. That way you can control in the DDM which fields are allowed to be searched on.

The various descriptor types are documented in more detail in Columns of Field Attributes in the section Using the DDM Editor of the Natural Editors documentation.

Descriptor Type - continued

The following rules apply:

• In an Adabas file, the descriptor must be D if type HM, HP, HQ, HY (all hyperdescriptors), OD (collation descriptor) or PH (phonetic descriptor) is specified.

• For a subdescriptor in an Adabas file, descriptor D and type SB (subfield) must be specified.

• For a superdescriptor in an Adabas file, descriptor D and type SP (superfield) must be specified.

• In a DB2 table or DB2 query table, if a key or index (descriptor D, E, F or P) includes more than one field, the type SP (superfield) must be specified

• In a VSAM file or userview (type L, R, V or W), the descriptor must be either P or A if type SP (superfield) is specified.

• If A is specified for a field of a VSAM file (type L or V), an additional screen is displayed for entering the required definitions (see below).

• Descriptor type must be blank for fields within a redefinition.

Maximum Number of Values / Occurrences

Maximum number of values for a multiple value field or occurrences of a periodic group is indicated in the Occ column of the Field List tab. This parameter must be specified for multiple value fields and for periodic groups in a redefinition.

When generating Copy Code, the value specified is used as the default for generating the specifications of MU/MC or PE/PC fields in a format buffer and/or record buffer.

When generating ADACMP/ADAFDU definitions, the Occ parameter is evaluated. If Occ is specified, the number of occurrences of each input data record is constant.

If Occ is not specified, the number of occurrences is taken from a counter field preceding a MU/MC or PE/PC field.

Note:
For fields of type QN, the Occ column is used to identify either the table level or an individual occurrence of a multiple value field or periodic group.

Unique Option

The unique option is indicated in column U of the Field List tab. For groups, this attribute must be blank; for other fields, one of the following values can be specified:

Unique option must be blank for fields within a redefinition.

Field Short Name

For file types listed below, the field short name is indicated in the column DB of the Field List tab. This two-character short name must be defined for the following file types:

A field short name must conform to the rules for coding Adabas field names.

Field short names for userviews of Adabas, IMS and VSAM files need not be unique.

For fields within a redefinition, parameter Field short name must be blank.

Field short names for SQL tables and views are maintained internally by Predict and cannot be modified by users.

Rotated fields of files of type A (with SQL usage), type AT and B have the same short name and are identified uniquely by an occurrence number (column Occ).

Suppression / Null Value Option

• For fields of Adabas files, the suppression option is indicated in column S of the Field List tab.

• For fields of SQL files, the null value option is indicated in column N of the Field List tab.

For groups and for fields within a redefinition, this attribute must be blank. For other fields, one of the following values can be specified:

Profile Parameter Automatic Null Value

With the profile parameter Automatic null value you can determine an automatic Suppression/Null Value option when fields are added in Predict. See Customizing Predict with Profiles in the section Predict User Interface in the Introduction to Predict documentation.

The value depends on the file type. See table below.

Dictionary View by default uses the profile SYSTEM.

Note:
SQL file types include files of type A with parameter Adabas SQL usage set to Y.

For DB2 fields with Unique option = unique, values R and U are possible.

Variable Length Option - IMS

The variable length option for IMS fields is indicated in column S of the Field List tab. The following values are valid:

Null Default Option

The NULL default option for fields of SQL tables/views is indicated in the column Df of the Field List tab. Possible values:

For Ingres fields with format OK or TK, the following additional values are possible:

This parameter must be blank for fields within a redefinition.

Natural Field Length

The Natural field length is shown in the dialog box which appears when you open a field (see Defining Additional Attributes of Fields). You can define it on the Base Extensions tab. The following rules apply:

• The parameter has to be specified if the field can be:

  • alphanumeric and greater than 253

  • graphic and greater than 126

  • numeric p.q (m/n) where p+q > 29 or q > 7.

    See table of valid formats and lengths in the section Field Length.

• The value specified here is the length that Natural can use for the field as defined in the DDM.

Do Not Convert Option

The "do not convert" option is allowed for A and AV format fields of the following file types:

• Adabas file/userview

• Conceptual file

This option is shown in the dialog box which appears when you open a field (see Defining Additional Attributes of Fields). You can define it on the Base Extensions tab.

Related Standard File

This parameter is described in the section Rippling.

Check against standard

This parameter is described in the section Rippling.

Natural Attributes

The following attributes can be defined in the Natural Attributes tab:

• Headers

• Index on PE Group Level

• Edit mask

• Dynamic length

Headers

The Natural headers are shown in the dialog box which appears when you open a field (see Defining Additional Attributes of Fields).

The Natural headers 1 - 3 are included in DDMs generated from the file containing the field.

Alphabetic characters in Natural headers are converted to upper-case if the Predict parameter Upper/lower case has been set to Y. See the section Defaults in the Predict Administration documentation.

Index on PE Group Level

This parameter is shown in the dialog box which appears when you open a field (see Defining Additional Attributes of Fields).

If this parameter is left blank (default), the maximum occurrences is generated for each element in the group.

Edit mask

The Natural edit mask. See the description of the DISPLAY statement in the Natural Statements documentation for further details.

This parameter is shown in the dialog box which appears when you open a field (see Defining Additional Attributes of Fields).

Alphabetic characters in the Natural edit mask are converted to upper-case if the Predict parameter Upper/lower case has been set to Y. See the section Defaults in the Predict Administration documentation.

Dynamic length

This parameter is shown in the dialog box which appears when you open a field (see Defining Additional Attributes of Fields).

Hidden

Specifies that the column is not visible in the result for SQL statements unless you explicitly refer to the column by name.

If you check the box, columns are not visible.

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