These names have been used for “dummy” stop controls which do not operate any stop. While Wedgwood characterizes them as “A facetious pleasantry indulged in by some mediaeval organ builders”, Mahrenholz points out that they were often provided for future expansion or for physical symmetry. The names translate as follows:

Blinder Zug	“blind stop”
Ductus inutilis	“useless stop”
Exaudire	"to hear plainly"
Manum de tabula	"Enough!"
Nihil	“nothing”
Pro forma	“for appearance”
Reliqua	"leftover"
Summer Zug	“silent stop”
Swyger	“keep silent”
Vacant	“missing”
Vacat	“missing”
Vox Inaudita	“unheard voice”
Vox Ineffabilis	“unutterable voice”

Examples

No examples are known of any of these names being engraved on stop controls. Contributions welcome.

Bibliography