# QvxFieldHeader element

The QvxFieldHeader element describes a single table field. It specifies the field name, format used to write the field values in the QVX formatted file, as well as how Qlik Sense or QlikView should interpret the values.

The elements Type, Extent, NullRepresentation, BigEndian, CodePage and ByteWidth describe how the field data values are written in the QVX formatted file.

FixPointDecimals and FieldFormat can be used to specify for Qlik Sense and QlikView how to interpret the read data values.

Field header elements

| Child Element | Description |
| --- | --- |
| FieldName | Field name. |
| Type | Data type in which field values are written in the QVX formatted data stream.<br><br>[QvxFieldType type](https://help.qlik.com/en-US/qlikview-developer/September2026/Subsystems/QVXSDKAPI/Content/QV_QVXSDKAPI/QlikView%20QVX%20File%20Format/QvxFieldType-type.htm). |
| Extent | Method used to define field value length.<br><br>[QvxFieldExtent type](https://help.qlik.com/en-US/qlikview-developer/September2026/Subsystems/QVXSDKAPI/Content/QV_QVXSDKAPI/QlikView%20QVX%20File%20Format/QvxFieldExtent-type.htm). |
| NullRepresentation | Method used to handle Null values.<br><br>[QvxNullRepresentation type](https://help.qlik.com/en-US/qlikview-developer/September2026/Subsystems/QVXSDKAPI/Content/QV_QVXSDKAPI/QlikView%20QVX%20File%20Format/QvxNullRepresentation-type.htm). |
| BigEndian | Order of bytes (with respect to significance) in data stream. It may be used for binary fields, that is, QVX\_SIGNED\_INTEGER, QVX\_UNSIGNED\_INTEGER and QVX\_REAL, also it may be used for byte count in QVX\_COUNTED fields. If not specified LittleEndian is assumed. |
| CodePage | Character encoding used to write field values in the QVX data stream. 1200/1201 implies UTF16. Byte order mark (BOM) is not allowed. BigEndian has no effect on UTF16. If not set then UTF8 is assumed. |
| ByteWidth | In case of QVX\_FIX fields, it is a size of the actual data:<br><br><ul> <li>1,2,4 or 8 for QVX_INTEGER_SIGNED and QVX_UNSIGNED_INTEGER.</li> <li>4 or 8 for QVX_IEEE_REAL.</li> <li>Arbitrary size for other QVX field types. </li> </ul><br><br>In case of QVX\_COUNTED fields, it is a size of the byte count value, which is used to store a size of the actual data. |
| FixPointDecimals | Fixed number of digits to the right of the radix point. Used together with QVX\_SIGNED\_INTEGER, QVX\_UNSIGNED\_INTEGER, QVX\_PACKED\_BCD. For instance, value 1234 is interpreted as 12.34 with FixPointDecimals = 2 and is interpreted as 123400 with FixPointDecimals = -2. |
| FieldFormat | Format specifies how Qlik Sense or QlikView should interpret the streamed data values.<br><br>[FieldAttributes type](https://help.qlik.com/en-US/qlikview-developer/September2026/Subsystems/QVXSDKAPI/Content/QV_QVXSDKAPI/QlikView%20QVX%20File%20Format/FieldAttributes-type.htm). |