Structure

A structure, comprising:

• first and second portions
• respectively having a serration in which peaks and valleys are continuous, and
• configured to adjust relative positions of the first and second portions in an adjustment direction by interlocking the peaks and valleys with each other, wherein the adjustment direction is a direction in which the peaks and valleys of the serration are continuous;
• a fixing portion configured to maintain a defined state, wherein the defined state is a state in which the peaks and valleys are interlocked with each other and the relative positions of the first and second portions are fixed;
• and
• a positioning mechanism
• provided on the second portion or the fixing portion, and
• having a contact portion configured to contact the first portion in the defined state in such a manner that a position of the interlock of the serration can be reproduced, and wherein:
• the positioning mechanism is configured to adjust the relative position of the contact portion with respect to the first portion in the adjustment direction in such a manner that the contact portion contacts the first portion in the defined state,
• the fixing portion has a screw hole,
• the positioning mechanism
• is provided on the fixing portion, and
• comprises a shaft portion having a screw thread, the contact portion in a flange shape is provided on an end of the shaft,
• the relative position of the contact portion is variable by screwing the shaft portion into the screw hole, and
• the structure is configured to adjust the relative position of the contact portion in the adjustment direction by preventing a rotation of the shaft portion with a stopper.