1. A method comprising: locating a first file that describes attributes allowed by multiple versions of network devices and constraints associated with each attribute; locating a second set of files that store version-based differences relating to the attributes allowed by the multiple versions of the network devices, where the second set of files further includes links to fields, in the first file, that correspond to the multiple versions of the network devices; extracting, using the links included in the second set of files, a set of constraints associated with the attributes of one or more of the network devices from the first file; and using the set of constraints for the attributes of the one or more of the network devices to validate configuration data for the one or more of the network devices.