... flspec computes the spectrum of the background fluctuations in EPIC Imaging data in different offaxis annular regions. ... Once the 'flatfielded' image is free from detected sources, its pixels are binned according to the input parameter binsize and classified as 'positive' (if they have more counts than the median in the image) and 'negative' pixels (less counts than the median). ... The positive and negative spectra are extracted with an spectral binning of 15 eV (MOS) and 5 eV (PN). ...