Trados save information of pre-sentence as hash value when registering translation memory.
Consequently, when an original sentence and a translation memory of pre sentence have the same context, this is a context match.
Actually, context hash value on translation memory has only one pre-sentence.
I think that important thing for appropriately translating is context.
However, it may change a translation context depending on some previous sentence of the segment.
In other words, if employing the way of this rule, I am worried that a translator may translate a sentence as context match without checking context.
Hence, I suggest that users can choose how many pre sentence need to calculate hash value of context.