Why are you interesetd in market/limit when oyu want to create OHLC ? You do not need market/limit information for that
I think it simply means what order type the executing order was. So the order resting in the orderbook was abviously a limit order.
But the order which is matching it can be placed as market order or as limit order.
In sense of fees a limit order you place, that directly matched existing orders, is usually counted as a "market order" -> taker fee.
But still it was placed as a limit order and I think that is what kraken is telling us with that entry.
But still not sure, why anyone would need this info.