
Originally Posted by
Tdol
As I understand it, this covers the learner's knowledge- they start with L1 and are given rules for L2, but they don't just jump straight to a perfect understanding, so they develop their own system, which changes over time as they increase in their understanding of the target language. This grammar, phonology, etc, they build up, which will be heavily influenced by L1 at first but will develop and change as their understanding increases, is the approximative system. As the person learns, it becomes closer step by step towards the target language.