From U of Edin. Lib. MS File La.IV.7.1
: Document 1
The name Lang is pretty common in England and doubtless the same as
Laing(1). The armorial Ensigns of one of them prove they are
derived of the same stock, as they bear the three piles, but in different
position and of different color.
Memo of the Armorial Ensigns of the Name of Laing or "Laying"
(1) Studies of the name indicate that they have indeed
often been interchangeable. The spelling Laing seems to have been
the most closely associated with the armorial bearings. The archaic
spelling is Layng although often it is found spelled Laying as well, this
possibly having been a transitional spelling.