def _get_fov_type(fov):
    "Return a FOV from a string"
    oldFOV = fov
    fov = str(fov).upper()
    if fov in _FOVTYPES:
        return _FOVTYPES[fov]
    if fov[:10] == 'PERMISSIVE' and fov[10].isdigit() and fov[10] != '9':
        return 4 + int(fov[10])
    raise _tdl.TDLError('No such fov option as %s' % oldFOV)
Return a FOV from a string