This read-write integer lets an admin manually assign this port's contribution to the internal MST path cost toward the region's root, complementing the read-only operational path cost object; writing 0 restores the automatically calculated default, and reading back 0 confirms the default is in use. An admin uses it to manually tune STP path selection on specific links rather than relying on speed-based defaults. For example, an engineer wanting to keep a particular redundant link as a backup rather than the preferred path would raise this value above the automatically calculated cost of the primary link.