  The X-Shooter Spectral Library (XSL) contains more than 800 spectra of stars
across the color-magnitude diagram, that extend from near-UV to near-IR
wavelengths (320-2450 nm). We summarize properties of the spectra of O-rich
Long Period Variables in XSL, such as phase-related features, and we confront
the data with synthetic spectra based on static and dynamical stellar
atmosphere models. We discuss successes and remaining discrepancies, keeping in
mind the applications to population synthesis modeling that XSL is designed
for.
