The wording in the article is interesting…
All varieties of the Scottish language are welcome, from echoes of the sixteenth-century masters Dunbar and Henryson to the regional dialects of Aberdeen and Orkney, Fife and the southwest. The vernacular patter of the cities is also acceptable (“Cum oan get aff the bus”sort of quip); the sharp humour of Scotland should certainly have a place. The judges will take a liberal attitude towards the predominance of Scots in the poems, as long as there is a sufficiency of Scottish vocabulary and/or idioms. After all, the great exemplar of the language, Burns himself, did not hesitate to use English words when they suited his purpose!