DICOM PS3.8 2016b - Network Communication Support for Message Exchange

9.3.3.3 User Information Item Structure
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#### 9.3.3.3 User Information Item Structure

The User Information Item shall be made of a sequence of mandatory length fields followed by a variable field. Table 9-20 shows the sequence of the mandatory fields.

The variable field shall consist of one or more User-Data Sub-Items.

### Note

The User-Data Sub-Items may be present in any order within the User-Information Item. No significance should be placed on the order of User-Data Sub-Items within the User Information Item. Sending applications should be aware that some older applications might expect Sub-Items to be encoded in ascending order of Item-type within the enclosing Item.

Table 9-20. User Information Item Fields

Item bytes | Field name | Description of field
--- | --- | ---
1 | Item-type | 50H
2 | Reserved | This reserved field shall be sent with a value 00H but not tested to this value when received.
3-4 | Item-length | This Item-length shall be the number of bytes from the first byte of the following field to the last byte of the User-data-information field(s). It shall be encoded as an unsigned binary number.
5-xxx | User-data | This variable field shall contain User-data sub-items as defined by the DICOM Application Entity. The structure and content of these sub-items is defined in Annex D.

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DICOM PS3.8 2016b - Network Communication Support for Message Exchange