Timing of ablaut

From: aquila_grande
Message: 25908
Date: 2003-09-19

Do enyone have a view about when and in what order the occurence of
the following types of ablaut/wovel changes occured?

quantitative ablaut (normal/zero-grades)

qualitative ablaut (e/o-grades)

coloring of wovels by laryngeals

quantitative ablaut (lengthened grade)