  Recent years have witnessed a steep increase in linguistic databases
capturing syntactic variation. We survey and describe 21 publicly available
morpho-syntactic databases, focusing on such properties as data structure, user
interface, documentation, formats, and overall user friendliness. We
demonstrate that all the surveyed databases can be fruitfully categorized along
two dimensions: units of description and the design principle. Units of
description refer to the type of the data the database represents (languages,
constructions, or expressions). The design principles capture the internal
logic of the database. We identify three primary design principles, which vary
in their descriptive power, granularity, and complexity: monocategorization,
multicategorization, and structural decomposition. We describe how these design
principles are implemented in concrete databases and discuss their advantages
and limitations. Finally, we outline essential desiderata for future modern
databases in linguistics.
