Identification of the source (7 columns)

SRCID (Long)
A unique number assigned to a unique source determined through source detection on the stack. The SRCID assignments in 5XMM bear no relation to those in 4XMM.
IAUNAME (String)
The IAU name assigned to the unique SRCID (see 3XMM-DR4 UG, Sec. 3.8.1 ).
OBS_ID (String)
The XMM-Newton observation identification.
PPS_SRCNUM (Integer) SAS task srcmatch
The (decimal) source number attributed to a detection by the automatic pipeline processing; when expressed in the hexadecimal system it identifies the source-specific product files belonging to this detection (2XMM UG Appendix A.1).
N_OBS (Integer)
The total number of observations per stack. The column value is set to null in the observation-specific rows and can thus be used to select the summary source rows per source, for example by the expression "N_OBS > 0".
N_CONTRIB (Integer)
The number of contributing observations for which the source position is inside the field of view. The column value is set to null in the observation-specific rows and can thus be used to select the summary source rows per source, for example by the expression "N_CONTRIB > 0".
N_EXP (Integer)
The number of exposures, i.e. the number of active instruments, and is set in each row of the catalogue.