This is a pilot study investigating the role of phrasal fixedness in the development of a standardised text type. The linguistic material comes from the Edinburgh Corpus of Older Scots (ECOS), consisting of samples of administrative records from 15th-century Scotland. The corpus has been searched for re-occurring lemmatic bundles, which are the indicators of emerging patterns and standardising usage in the records, developing in the context of linguistic standardisation of Scots. The findings are interpreted with regard to their semantics and function in the records, and indicate that the text type as such was not yet fully standardised in its repertoire of fixed phrases serving a specific purpose. In individual locations, however, one finds a greater degree of consistency and a tendency to develop a local norm. Similarly, in some specific textual functions the lexical fixedness may be present to a larger extent than in others.