OMX is a binary matrix format to store OD-data using the HDF5 compression standard designed to sort and organize large amounts of data, and is supported by The HDF Group (https://www.hdfgroup.org/).
The advantages of OMX compared to traditional ASCII-based formats are:
♦ Smaller file sizes
♦ Reduced read/write times
♦ Increased data precision – data is stored in floating point format rather than fixed decimal places
OMX files may include one or more "tables", each table being a single matrix of the same size (number of rows and number of columns). They therefore can hold, for example, ‘stacked’ demand by user class or multiple component skim matrices.