And Shakalnokturn did just prove that I was wrong. The one I'm after is not the B1024, but the B1023.

So we have the following Designations:

1st Series

B1020 (no buttons - no additional functions, no RMS) Gossen:

?, Norma:

?

B1021 (8 buttons - Hold, MinMax, manual range, RMS?) Gossen: MAVO20, Norma: MP12

B1022 (15 buttons - as above, +dB, Limits, frequency and type K temp., RMS) Gossen: MAVO30, Norma: MP13

B1023 (15 buttons - as above, + time recording, RMS) Gossen:

?, Norma: MP14

The B1022 and the B1023 are distinguishable by the second pushbutton from the right in the lowest row, which is only +/- on the 1022 and has a shift function 'Time' on the B1023) And 'Time' does not mean merely elapsed time, but you can set a RTC and any min/max event or limit violation will be recorded with the time of occurrence.

THAT is the function I'm after. And now we know that I don't get it with the MAVO30.

then came a second series in the same form factor:

B1024, which has 4 pushbuttons and no current range, but a special range for current clamps with voltage output. It could also do temperature by PT100 and AC voltage with 1kOhm/V.

B1025, which has 6 pushbuttons, normal current ranges and all of the above plus min/max, and a range for current clamps with current output.

B1026, with 7 pushbuttons, RMS, all of the above + frequency, capacitance and a backlight.

B1027, which I do not know

B1028, with 11 pushbuttons, TRMS, all of the above, plus relative, limits and a zoom function for the bargraph.

I do not know, whether there were Norma/Gossen equivalents to those later ones. There is a Norma DMM950 with the same form factor, which has 12 PB. Here is some additional info:

https://sigrok.org/wiki/Norma_DM950but that can't be totally correct regarding the equivalencies.

Remarks:

The first series was listed in the Siemens catalogue of 1987, together with the new analogue/digital hybrid B1012.

The Gossen models were all BEFORE Gossen did go together with Metrawatt.

The later series is often seen with a rubber protector, the earlier ones not.