Table 3: Criteria adopted to separate the secondaries with multi-color observations into confirmed companions, candidate companions, and background stars. The $\chi ^2$ values of 2.30 and 11.8 correspond to the $1\sigma$ and $3\sigma$ levels. This means that (statistically) 68.3% of the physical companions have $\chi ^2 < 2.30$ and 99.73% of the physical companions have $\chi ^2 < 11.8$ . A secondary with $\chi ^2 < 2.30$ is very likely a companion star. A secondary with $\chi ^2 > 11.8$ is almost certainly a background star. The secondaries with $2.30 < \chi ^2 < 11.8$ may be companions or background stars.
Secondary status Symbol Criterion

Confirmed companion c $\chi ^2$ $\leq 2.30$

Candidate companion ? 2.30< $\chi ^2$ $\leq 11.8$

Background star b 11.8< $\chi ^2$

**Table 3:** Criteria adopted to separate the secondaries with multi-color observations into confirmed companions, candidate companions, and background stars. The $\chi ^2$ values of 2.30 and 11.8 correspond to the $1\sigma$ and $3\sigma$ levels. This means that (statistically) 68.3% of the physical companions have $\chi ^2 < 2.30$ and 99.73% of the physical companions have $\chi ^2 < 11.8$ . A secondary with $\chi ^2 < 2.30$ is very likely a companion star. A secondary with $\chi ^2 > 11.8$ is almost certainly a background star. The secondaries with $2.30 < \chi ^2 < 11.8$ may be companions or background stars.
Secondary status	Symbol	Criterion
Confirmed companion	c		$\chi ^2$	$\leq 2.30$
Candidate companion	?	2.30<	$\chi ^2$	$\leq 11.8$
Background star	b	11.8<	$\chi ^2$

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