Intel® Fortran Compiler 16.0 User and Reference Guide
The BN and BZ descriptors control the interpretation of embedded and trailing blanks within numeric input fields. These descriptors have no effect during execution of output statements.
Within a format specification, a blank editing descriptor affects all subsequent I, B, O, Z, F, E, EN, ES, D, and G descriptors until another blank editing descriptor occurs.
The blank editing descriptors override the effect of the BLANK specifier during execution of a particular input data transfer statement. (For more information, see the BLANK specifier in OPEN statements.)