Objects are flagged if they lie within masked regions of the 12 input
images, or beyond the image boundaries.

Mask flags are generated by summing the individual flag values in the
table below, e.g. a flag value of 72 indicates individual flags of
8+64 (i.e. object lies within Y + JHK masks).

The SXDS extended stellar halo regions have not been found to have a
significant influence on photometry.

The masking flags are:

1  - source overlaps with SXDS extended 'halo' regions
2  - source overlaps with SXDS masked regions (bright sources and CCD bleeds)
4  - source aperture extends off the SXDS image
8  - source overlaps with Y-band masked regions [NB Highlights only additional regions not in SXDS bright mask]
16 - source overlaps with any IRAC masked regions
32 - source overlaps with deeper (SEDS or SpUDS) IRAC masked regions
64 - source overlaps with JHK masked regions
128 - source aperture extends off the UDS image

NB: SXDS refers to the Subaru B,V,R,i',z' imaging. 

Note that there is no explicit U-band mask. The U-band masked regions
were found to lie within the SXDS mask.

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The pre-defined subsets ("best" and "good") apply the following flags. Note that cross-talk are removed separately.
 
Good: maskflag = 0,1,32,33
Best: maskflag = 0,1