Assertion: sextant's error | /r/HasProperty | introduced
Facets:
Source sentences:
text: The index mirror must be perpendicular to the sextant frame, otherwise an error is introduced.
text: The horizon glass must be perpendicular to the frame of the sextant, otherwise an error is introduced.
text: The horizon glass must be parallel to the index mirror when the sextant is set on zero, otherwise an error is introduced.
text: The telescope must be parallel to the frame, otherwise an error is introduced.