The ornamental design for an attachableexternalvehiclesign, as shown and described.
FIG. 1 is a perspective view of the attachable external vehicle sign, shown with environment.
FIG. 2 is a front elevational view of the attachable external vehicle sign, shown with environment.
FIG. 3 is a rear elevational view of the attachable external vehicle sign.
FIG. 4 is a right side elevational view thereof.
FIG. 5 is a left side elevational view thereof.
FIG. 6 is a top plan view of the attachable external vehicle sign, with environment.
FIG. 7 is a bottom plan view of the attachable external vehicle sign; and,
FIG. 8 is a second perspective view of the attachable external vehicle sign, shown with environment.
The broken lines showing in FIGS. 1,2,6, and 8, are for the purpose of illustrating the environment of the article only and form no part of the claimed design.