The format for 1d spectra is particularly simple. Each z1d file is a binary file containing NSIZE 16-bit or 32-bit words, where NSIZE is the number of channels in the spectrum. The word length is 16-bit (single word) or 32-bit (double word) according to the option chosen in the setup. So the file size will is NSIZE*2 bytes or NZISE*4 bytes, depending on whether it is 16-bit or 32-bit. Note that the file itself contains no information about whether the data is 16-bit or 32-bit.