Polarization pseudo-spectroheliograms of 2001 June 15th two-ribbon flare derived from four observing time sets. Intensity levels are in grey. y axis is labeled in arcsec. Each x axis label identifies a narrow 2D spectra in a set of eleven adjacent and successive 2D spectra of wavelength width 0.032 nm, covering 11 pixels. They correspond to scans made along the x direction (with a δx 2.5 arcsec scan step). Regions with Na D2 linear polarization degree higher than 3%, and with either tangential or radial polarization directions are in black or white. On the 10H 07M 20S pseudo-spectroheliogram, four letters, A, B, C, D, indicate locations where line intensity, polarization degree and orientation profiles were computed (see Fig. 5).