What is "middle scots"

Middle Scots was the Anglic language of Lowland Scotland in the period from 1450 to 1700. By the end of the 15th century, its phonology, orthography, accidence, syntax and vocabulary had diverged markedly from Early Scots, which was virtually indistinguishable from early Northumbrian Middle English. Subsequently the orthography of Middle Scots differed from that of the emerging Early Modern English standard. Middle Scots was fairly uniform throughout its many texts, albeit with some variation due to the use of Romance forms in translations from Latin or French, turns of phrases and grammar in recensions of southern texts influenced by southern forms, misunderstandings and mistakes made by foreign printers.