The OVF 0.0 format (formerly SVF) is an older, simpler format that can be useful for importing three-dimensional vector field data into OOMMF from other programs. (A fourth format, the VecFil or Vector Input/Output (VIO) format, was used by some precursors to the OOMMF code. Although OOMMF is able to read the VIO format, its use is deprecated.)
In all these formats, the field domain (i.e., the spatial extent) lies across three dimensions, with units typically expressed in meters or nanometers. In all the formats except the OVF 2.0 format, the field values are also three dimensional; the value units are more varied, but are most often Tesla or A/m. The OVF 2.0 format is more general, in that the field values can be of any arbitrary dimension N > 0. (This dimension, however, is fixed within the file.) If N = 3, then the OVF 2.0 format supports the same types of data as the OVF 1.0 format, but another common case is N = 1, which represents scalar fields, such as energy density (in say, J/m3).
The recommended file extensions for OVF files are .omf for magnetization files, .ohf for magnetic field (H) files, .obf for magnetic flux density (B) files, .oef for energy density files, or .ovf for generic files.