2 Corinthians 3:4-11; Psalm 98(99):5-9; Matthew 5:17-19
Jesus' good news does not over-write the previous covenant between God and his creation, mankind. In todays Gospel from Mark, Jesus clearly states that all of the old laws - based on the 5 books of scriptures that are collectively called the Pentateuch, stand forever - they still apply today.
However Jesus does complete them. So we do need to pay attention when he quotes from them - he usually adds an emphasis and makes clear the real meaning of them. Often He does this by practice - such as asking the crowd, who will cast the first stone? Because if you do, then you will be judged by the same law. None of us is perfect, so none of us can cast that stone.
The dots and strokes that Jesus refers to are a feature of Hebrew text. They work somewhat as vowels in English text, and so can change the meaning of a word completely. It is therefore very important when reading Hebrew (which I can't!!) to observe them - so really Jesus is saying that we need to study these texts carefully, looking for every small detail that can bring meaning to them. Fortunately we have in our diocese some skilled at this.
If you have the time - watch the recorded talks given by John Huntriss on our website (there are several more at the Diocesan website). John is a skilled interpreter of the scriptures, and can help us to understand the texts in a way that makes them relevant to our lives today.