($\boldsymbol S$ = $\boldsymbol C$ = $\boldsymbol B$ = 0)
For $\mathit I = 1$ (${{\mathit \pi}}$, ${{\mathit b}}$, ${{\mathit \rho}}$, ${{\mathit a}}$): ${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit d}}}$, ( ${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit u}}}−$ ${\mathit {\mathit d}}$ ${\mathit {\overline{\mathit d}}})/\sqrt {2 }$, ${\mathit {\mathit d}}$ ${\mathit {\overline{\mathit u}}}$;
for $\mathit I = 0$ (${{\mathit \eta}}$, ${{\mathit \eta}^{\,'}}$, ${{\mathit h}}$, ${{\mathit h}^{\,'}}$, ${{\mathit \omega}}$, ${{\mathit \phi}}$, ${{\mathit f}}$, ${{\mathit f}^{\,'}}$): ${\mathit {\mathit c}}_{{\mathrm {1}}}$( ${{\mathit u}}{{\overline{\mathit u}}}$ $+$ ${{\mathit d}}{{\overline{\mathit d}}}$ ) $+$ ${\mathit {\mathit c}}_{{\mathrm {2}}}$( ${{\mathit s}}{{\overline{\mathit s}}}$ )
INSPIRE search

${{\boldsymbol \eta}{(1295)}}$ $I^G(J^{PC})$ = $0^+(0^{- +})$ 

See the review on "Pseudoscalar and pseudovector mesons in the 1400 MeV region."
${{\mathit \eta}{(1295)}}$ MASS   $1294 \pm4$ MeV (S = 1.6)
${{\mathit \eta}{(1295)}}$ WIDTH   $55 \pm5$ MeV 
$\Gamma_{1}$ ${{\mathit \eta}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$  seen 487
$\Gamma_{2}$ ${{\mathit a}_{{0}}{(980)}}{{\mathit \pi}}$  seen 248
$\Gamma_{3}$ ${{\mathit \gamma}}{{\mathit \gamma}}$  647
$\Gamma_{4}$ ${{\mathit \eta}}{{\mathit \pi}^{0}}{{\mathit \pi}^{0}}$  seen 490
$\Gamma_{5}$ ${{\mathit \eta}}{({\mathit \pi}{\mathit \pi})_{{\mathit S}-{\text{wave}}}}$  seen
$\Gamma_{6}$ ${{\mathit \sigma}}{{\mathit \eta}}$ 
$\Gamma_{7}$ ${{\mathit K}}{{\overline{\mathit K}}}{{\mathit \pi}}$  320