For this example the coefficients are signed with a coefficient width of 10 bits and a coefficient fractional width of 5 bits (using the Mathworks Fix format notation Fix10_5). The specified coefficients range between -12.34 and +13.88.
Considering the coefficient bit width as integer only, 10 bits give a maximum positive value of 511 and a maximum negative value of -512. The fractional bit width is 5 bits; this gives a maximum representable positive number of 511/(2^5)=15.96875 and a maximum representation negative number of -512/(2^5)=-16. All coefficients are scaled by the factor 15.96875/13.88=1.1504863 (=+1.2176dB) prior to quantization. The overall scaling factor is calculated as defined previously and displayed in the Vivado IDE.