### $\pm $ sign pattern matrices that allow orthogonality

A sign pattern $A$ is a $\pm $ sign pattern if $A$ has no zero entries. $A$ allows orthogonality if there exists a real orthogonal matrix $B$ whose sign pattern equals $A$. Some sufficient conditions are given for a sign pattern matrix to allow orthogonality, and a complete characterization is given for $\pm $ sign patterns with $n-1\le {N}_{-}\left(A\right)\le n+1$ to allow orthogonality.