Relative intensity of the G316.8−0.1 (“on-source”) subtracted from the average of three sources of its environment (“off-source”). Higher-intensity absorption would indicate the location of the H II region. The vertical line at −40 km s⁻¹ shows the velocity of the ¹³CO (1−0) molecular line (emission) detected with the MSX survey by Busfield et al. (2006). The horizontal light blue line shows the zero value from which the absorption intensity is measured.