The ornamental design for a captivescrew, as shown and described.
FIG. 1 is a left side elevation of a captive screw showing my new design;
FIG. 2 is a right side elevation thereof;
FIG. 3 is a perspective view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a top plan view thereof showing a six lobed driver recess;
FIG. 6 is an alternate top plan view thereof showing a combined six lobed/slotted driver recess;
FIG. 7 is an alternate top plan view thereof showing a slotted driver recess;
FIG. 8 is an alternate top plan view thereof showing a Phillips driver recess; and,
FIG. 9 is an alternate top plan view thereof showing a combined slotted/Phillips driver recess.
The broken lines immediately adjacent the claimed areas represent the bounds of the claimed design while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the claimed design.