Our primordial item (~10 years ago) was to use short “unresolved” spikes, which are seen within individual pulses in some pulsars after dispersion removal (Hankins 1971) for precise measurements of dispersion measure (DM). For this purpose we performed three-frequency observations in the 60-102 MHz frequency range for PSR 0950+08, 0809+74 and 1133+16 (Novikov et al. 1983). The result was that “classical” microstructure (with 0.2, 1.2, and 0.55-ms time scales, respectively) is well correlated over this frequency range, but those bursts with a shorter duration (~100μs) do not show any correlation. In particular, no coincidence of the short “unresolved” spikes at two different frequencies was detected. On the basis of these results we reduced the frequency spacing to 1-2 MHz, but the result was the same (Popov et al. 1985).