E-formats (see 2.8.3) avoid problems when matrix cells contain both very large and very small values. For example, take 2 cells with values 12345.67 and 0.0001234567. Under E-formats (with 7 decimal places) they would be output as 0.1234567E+06 and 0.1234567E-03, whereas under decimal outputs they would become 12345.670000 and 0.0001235. In this case decimal outputs lose precision with the smaller outputs while E-formats do not.
For maximum precision, minimum loss of accuracy it is recommended that users choose E-formats with 7 decimal places as this corresponds roughly to the numerical precision of single-precision real variables on the computer. Lack of precision may be a serious problem if a matrix is being dumped to text in order to export it to, say, EXCEL, manipulate it and then return it to MX. For “one-way” transfers precision may be less of an issue.