def _initSymbols(ptc):
    """
    Initialize symbols and single character constants.
    """
      # build am and pm lists to contain
      # original case, lowercase and first-char
      # versions of the meridian text

    if len(ptc.locale.meridian) > 0:
        am     = ptc.locale.meridian[0]
        ptc.am = [ am ]

        if len(am) > 0:
            ptc.am.append(am[0])
            am = am.lower()
            ptc.am.append(am)
            ptc.am.append(am[0])
    else:
        am     = ''
        ptc.am = [ '', '' ]

    if len(ptc.locale.meridian) > 1:
        pm     = ptc.locale.meridian[1]
        ptc.pm = [ pm ]

        if len(pm) > 0:
            ptc.pm.append(pm[0])
            pm = pm.lower()
            ptc.pm.append(pm)
            ptc.pm.append(pm[0])
    else:
        pm     = ''
        ptc.pm = [ '', '' ]