a  For sources CX148 and CX149, and for CX146, CX147 and CX150-158,
a  that were only detected in the hard and soft band respectively,
a  positions and count(rate)s are derived from the hard and soft
a  band.

b  CX54: properties may be affected by a bad-pixel region.

c  CX4, CX13, CX54: identification with ROSAT source is uncertain.

d  CX6, CX24, CX47, CX139, CX141: the optical counterparts are not
d  included in the EIS catalogue, or (for S1237) the EIS position is
d  clearly offset from the centre of the optical source. For these
d  sources, the number in the last column dOX refers to the distance
d  between the optical position from Fan et al., 1996AJ....112..628F,
d  and the X-ray position (corrected for the systematic offset with
d  respect to the Fan et al. catalogue:
d  delta(RA)=0.11+/-0.35arcsec, delta(DE)=0.23+/-0.29arcsec.)

e  CX46: besides the faint counterpart, two optical sources lie
e  inside the source region but further away from the X-ray source:
e  E1243 at 4.2arcsec, and S778 at 3.7arcsec.

f  CX30, CX34, CX35, CX54: ACIS-S sources; optical counterpart only
f  found when we use 2-sigma 'wavdetect' errors. For CX30 and CX35
f  the counterpart is only found for the total-band source. For CX34
f  and CX54 the counterpart is only found for the soft source;
f  therefore, the number in the last column d_XO refers to the
f  distance between the optical source and the soft source. See also
f  Sect.2.3 of paper.

g  CX26, CX50, CX80: ACIS-S sources; optical counterpart only found
g  when we use 3-sigma 'wavdetect' errors. For CX50 and CX80 the
g  counterpart is only found for the soft source; therefore, the
g  number in the last column dXO refers to the distance between the
g  optical source and the soft source. See also Sect.2.3 of paper.

h  CX32, CX45, CX53, CX62, CX67, CX73, CX86, CX129, CX149, CX152,
h  CX155: optical counterpart lies outside error box but inside the
h  source region (we only indicate cases for which the distance
h  between the X-ray and optical positions are less than 4-arcsec).