Both frames ( ^7X C2559 and H9X C2519) were built in the autumn of 1990, at a time when the "Stuttgart pattern" was still remembered and popular and the "Telekom pattern" was already approved and shown in catalogues for 1991.
As a rule, when the new "painting pattern" appeared, it appeared "in advance", i.e. in September of the year preceding the "catalogue debut" at the latest (because it was then - at the latest - that photos were taken for catalogues for the following year). For example, the 1993 catalogue showed models and painting patterns existing as early as August/September 1992... but it did not show all the models, modifications (and sometimes paintings) actually available on sale since the beginning of 1993... The 1993 catalogue is exemplary in this respect: it shows the early versions of Mx Leader produced only in 1992, but it does not show the final version from 1993; Merckx Donnay is an extreme example because production was completed as late as autumn 1992 (the traditional Donnay bankruptcy)
General rule: a calendar year has nothing to do with a year in the cycling business
D A9174 - built in 1988; it was a period when one tried to mark frames carefully with codes of a tube or model type... Unfortunately, it was also a period of introduction of new models of Century 653 and Grand Prix (753), which did not have any code markings... The most important difference was the chrome plating scheme (see EMC catalogue 1989) - but there were exceptions to the rule...
H F2533 - built in the middle of 1994; and this is the period when the careful marking of frames with a full set of codes began to be abandoned... and probably most models were built
Mx Leader, Corsa Extra, Century, Arcobaleno early, Corsa, Corsa Thron, Corsa 01 early, Corsa 01 late, Strada, Strada OS, Titanal, Alu Oria, Titane, Titane EM and Trekking, Cyclocross, Pista, Lady...and Corsa Extra 26' - I certainly forgot something
Photos are always welcome...