Maintain offers you a great deal of flexibility when naming and referring to procedure components, such as fields, functions, Winform buttons, and stacks. (Maintain functions are also known as cases.) When naming a component, be aware of the following guidelines:

• Length of names. Unqualified names that are defined in a Maintain procedure (such as the unqualified names of Winforms, functions, and stacks) can be up to 66 characters long.

  There is no limit on the length of a qualified name, as long as the length of each of its component unqualified names does not exceed 66 characters.

  Master File names, and names defined within a Master File (such as names of fields and segments), are subject to standard Master File language conventions, as defined in Describing Data

  Procedure name length is dependent on the operating system. On the Mainframe, procedure names can be a maximum of eight characters long.

• Valid characters in a name. All names must begin with a letter, and can include any combination of letters, numbers, and underscores ( _ ).
• Identical names. Most types of items in a Maintain procedure can have the same name. The only exceptions are data sources, stacks, and Winforms, which cannot have the same name within the same Maintain procedure. Most types of items in a Maintain procedure can have the same name, but this is not recommended.

  For example, you may give the same name to fields in different segments, data sources, and stacks, and to controls (also known as objects) in different Winforms, as long as you prevent ambiguous references by qualifying the names. A data source, a stack, and a Winform used in the same procedure can never have the same name.

• Qualified names. In general, whenever you can qualify a name, you should do so.

  Maintain requires that the qualification character be a period (.); the QUALCHAR parameter of the SET command must therefore be set (to the default).

  If a qualified name cannot fit onto the current line, you can break the name at the end of any one of its components, and continue it onto the next line. The continued name must begin with the qualification character. In the following example, the continued line is indented for reader clarity:

  FOR ALL NEXT ThisIsAVeryLongDataSourceName.ThisIsAVeryLongSegmentName
  .ThisIsAVeryLongFieldName INTO CreditStack;

  You can qualify the names of:

  • Controls. You can qualify a control name with the name of the Winform in which it is found. For example, if a button named UpdateButton is in a form named CreditForm, you could refer to the button as:

    CreditForm.UpdateButton

  • Member functions and member variables. When referring to an object's member functions and member variables, you should always use the function's or variable's fully-qualified name (that is, the name in the Winform objectname.functionname or objectname.variablename).
  • Fields and columns. You can qualify a variable name with the name of the data source, segment, and/or stack in which it is found, using a period (.) as the qualification character.

  Qualification is important when you are working with two data sources in one Maintain procedure, and the data sources have field names in common; when a field is present in both a data source and a stack, but it is not clear from the context which one is being referred to; and when different Winforms in the same procedure include identically-named controls.

  For example, both the Employee and JobFile data sources have a field named JobCode. If you want to issue a NEXT command for the JobCode field in Employee, you would use a qualified field name:

  NEXT Employee.JobCode;

  You can qualify a field name with any combination of its data source, segment, and stack names. When including a stack name, you have the option of specifying a particular row in the stack. If you use several qualifiers, they must conform to the following order:

  stackname(row).datasourcename.segmentname.fieldname

  If you refer to a field using a single qualifier (such as Sales) in the example

  Sales.Quantity

  and the qualifier is the name of both a segment and a stack, Maintain assumes that the name refers to the stack. To refer to the segment in this case, use the data source qualifier.

• Truncated names. You must spell out all names in full. Maintain does not recognize truncated names, such as Dep for a field named Department.
• Name aliases. You cannot refer to a field by its alias in a Maintain procedure. (An alias is defined by a field's ALIAS attribute in a Master File.)