Message Sets: CWF properties for embedded simple type binary types

Physical representation, byte alignment, and occurrences.

The Custom Wire Format properties described here apply to:

Objects: Embedded simple types

Physical representation

Property	Type	Meaning
Length	Button and Integer	If you have selected the length to be defined by Length, enter the number of length units for the element. The minimum value that you can specify is `1`. The maximum value that you can specify is `2147483647`. The default value is empty (not set).
Length Reference	Button and Enumerated type	If you have selected the length to be defined by Length Reference, select the name of the integer object that specifies the length of this object. Make your selection from the displayed list of integer objects that are defined as siblings of the current object, and occur before it in the structure of the message. For information about reordering elements, see Message Sets: Reordering objects.
Length Units	Enumerated type	Select the unit of length for the element or attribute. Select one of the following options from the displayed list (some physical types do not offer all these options): `Bytes`. The length is given in bytes. `Characters`. The Length is given in characters. This means that the number of bytes that are processed in the bitstream depends on the code page of the characters that are being processed. For a single-byte code page (SBCS CCSID) such as "latin-1" (CCSID 850), the number of bytes is equal to the number of characters. For a double-byte code page (DBCS CCSID) such as "UTF-16" (CCSID 1200), the number of bytes is exactly twice the number of characters. For a multibyte code page (MBCS CCSID) such as "UTF-8" (CCSID 1208), the number of bytes depends on the bitstream content. The parser reads one character at a time and determines whether the character comprises one or more bytes. `Character Units`. This option specifies that the size of each character (in bytes) is determined by the code page of the message. For single-byte and double-byte code pages, this option is identical to `Characters`. For a multibyte code page, this option provides improved parsing performance by assuming that every character is encoded in the smallest character unit that the code page supports. However, this means that a message must contain only these characters if it is to be processed correctly. For example, in code page "UTF-8" (CCSID 1208), the minimum character unit is 1 byte; therefore, the parser can make a single read (of the number of bytes specified by the `Length` property) to fetch the entire message. The message must contain only characters that are encoded in 1-byte units. `End of Bitstream`. All data up to the end of the bitstream is processed. This option is valid only if the element is the last in the message. If you select this value, you do not need to enter a value for the Length Count or Length Reference property. The default is `Bytes`.

Property

Type

Meaning

Length

Button and Integer

If you have selected the length to be defined by Length, enter the number of length units for the element.

The minimum value that you can specify is 1.

The maximum value that you can specify is 2147483647.

The default value is empty (not set).

Length Reference

Button and Enumerated type

If you have selected the length to be defined by Length Reference, select the name of the integer object that specifies the length of this object. Make your selection from the displayed list of integer objects that are defined as siblings of the current object, and occur before it in the structure of the message.

For information about reordering elements, see Message Sets: Reordering objects.

Length Units

Enumerated type

Select the unit of length for the element or attribute. Select one of the following options from the displayed list (some physical types do not offer all these options):

Bytes. The length is given in bytes.
Characters. The Length is given in characters. This means that the number of bytes that are processed in the bitstream depends on the code page of the characters that are being processed.
- For a single-byte code page (SBCS CCSID) such as "latin-1" (CCSID 850), the number of bytes is equal to the number of characters.
- For a double-byte code page (DBCS CCSID) such as "UTF-16" (CCSID 1200), the number of bytes is exactly twice the number of characters.
- For a multibyte code page (MBCS CCSID) such as "UTF-8" (CCSID 1208), the number of bytes depends on the bitstream content. The parser reads one character at a time and determines whether the character comprises one or more bytes.
Character Units. This option specifies that the size of each character (in bytes) is determined by the code page of the message.
- For single-byte and double-byte code pages, this option is identical to Characters.
- For a multibyte code page, this option provides improved parsing performance by assuming that every character is encoded in the smallest character unit that the code page supports. However, this means that a message must contain only these characters if it is to be processed correctly. For example, in code page "UTF-8" (CCSID 1208), the minimum character unit is 1 byte; therefore, the parser can make a single read (of the number of bytes specified by the Length property) to fetch the entire message. The message must contain only characters that are encoded in 1-byte units.
End of Bitstream. All data up to the end of the bitstream is processed. This option is valid only if the element is the last in the message. If you select this value, you do not need to enter a value for the Length Count or Length Reference property.

The default is Bytes.

Byte alignment

Property	Type	Meaning
Byte Alignment	Enumerated type	Specify how the object is aligned from the start of the message. Select one of: `1 Bytes`. The default value. `2 Bytes` `4 Bytes` `8 Bytes` `16 Bytes`
Leading Skip Count	Integer	Specify the number of bytes to skip before reading or writing this object. The default is `0`, the minimum value is `0`, and the maximum value is `999999`. You can use this value to ignore unwanted fields in a structure, or to model a field defined by C or COBOL data which requires alignment on a 2, 4, 8 or 16 byte boundary. Specify the number of bytes to skip before reading or writing this object. When an output message is written, Skip Count bytes are assigned the value of the message set Byte Alignment Pad property. For repeating objects, this property is applied to the first instance only.
Trailing Skip Count	Integer	Specify the number of bytes to skip after reading or writing this object. The default is `0`, the minimum value is `0`, and the maximum value is `999999`. You can use this value to ignore unwanted fields in a structure, or to model a repeating structure containing fields which require alignment on a 2, 4, 8 or 16 byte boundary. When an output message is written, Skip Count bytes are assigned the value of the message set Byte Alignment Pad property. For repeating objects, this property is applied to all instances.

Occurrences

Property	Type	Meaning
Repeat Reference	Enumerated type	Use this property if the object occurs multiple times, and the number of occurrences is given dynamically by a field earlier in the message. Select an integer object from the displayed list of integer objects that occur before this object in the structure of the message. The value of the selected integer specifies the number of occurrences of this object. If no objects are listed, there are no integer objects before this one in the message structure. If a Repeat Reference is specified, it overrides any setting for the Max Occurs logical property when parsing and writing the message, but not for validation of the message.