Detailed Description

on XML FLD files.

This class is the default for Nektar++ output. It reads and writes one XML file per processor that represents the underlying field data. For serial output, the format of an XML file obeys the following structure:

``` <NEKTAR> <Metadata> ... </Metadata> <ELEMENT FIELDS="..." ...> data1 </ELEMENT> <ELEMENT FIELDS="..." ...> data2 </ELEMENT> ... </NEKTAR> ```

Metadata is converted as key/value pairs in the <Metadata> tag.
There are one or more ELEMENT blocks, whose attributes correspond with the FieldDefinitions class variables.
Element data is stored as a base64-encoded zlib-compressed binary double-precision data using the functions from CompressData.

In parallel, each process writes its contributions into an XML file of the form P0000001.fld (where 1 is replaced by the rank of the process) inside a directory with the desired output name. These files only include the ELEMENT data. Metadata are instead stored in a separate Info.xml file, which contains the Metadata and additional tags of the form

<Partition FileName="P0000000.fld"> ID list </Partition>

The ID list enumerates all element IDs on each partition's contribution. For large parallel jobs, this is used to avoid each process reading in every single partition in order to load field data.