Features

VTK XML Exporters

Serial datasets

Topology	Extension	Status
Image Data	.vti	—
Polydata	.vtp	—
Rectilinear Grid	.vtr	✅
Structured Grid	.vts	✅
Unstructured Grid	.vtu	✅

Parallel (partitioned) datasets

Topology	Extension	Status
Parallel Image Data	.pvti	—
Parallel Polydata	.pvtp	—
Parallel Rectilinear Grid	.pvtr	—
Parallel Structured Grid	.pvts	✅
Parallel Unstructured Grid	.pvtu	—

Composite datasets

Type	Extension	Status
vtkMultiBlockDataSet	.vtm	✅

VTK Legacy Exporters

Topology	Status
Structured Points	✅
Structured Grid	✅
Unstructured Grid	✅
Rectilinear Grid	✅
Polydata	—
Field	—

Output Formats

Format	Description
ascii	Human-readable text inside XML elements
binary	Base64-encoded binary inside XML elements
raw	Raw binary in the XML appended section (with byte offsets)
binary-appended	Base64-encoded binary in the XML appended section

The format string passed to initialize is case-insensitive.

Global Field Data

Optional simulation metadata (time, cycle number, dataset name, etc.) can be attached before the first piece via write_fielddata:

error = a_vtk_file%xml_writer%write_fielddata(action='open')
error = a_vtk_file%xml_writer%write_fielddata(x=0._R8P, data_name='TIME')
error = a_vtk_file%xml_writer%write_fielddata(x=1_I8P,  data_name='CYCLE')
error = a_vtk_file%xml_writer%write_fielddata(action='close')

Data Arrays

write_dataarray is a heavily overloaded interface that accepts:

• All PENF numeric kinds: R8P, R4P, I8P, I4P, I2P, I1P
• Ranks 1–4 for dense arrays
• Scalar, 1-component, 3-component (vector), and 6-component (symmetric tensor) layouts
• Node-centered or cell-centered placement (location='node' or location='cell')

Parallel Support

VTKFortran can safely manage multiple concurrent open files. It is thread/processor safe, suitable for use within OpenMP parallel regions and MPI programs where each rank writes its own partition file.

Compiler Support

Compiler	Status
GNU gfortran ≥ 6.0.1	✅ Supported
Intel Fortran ≥ 16.x	✅ Supported
IBM XL Fortran	Not tested
g95	Not tested
NAG Fortran	Not tested
PGI / NVIDIA	Not tested

Design Principles

• Pure Fortran — no external C libraries or system calls beyond standard I/O
• OOP — polymorphic xml_writer allocated at runtime; vtk_file, pvtk_file, vtm_file expose type-bound procedures
• KISS — simple, focused API without unnecessary abstractions
• Error codes — every procedure returns an integer; zero means success
• Free & Open Source — multi-licensed for FOSS and commercial use