The Washington Nationals have until tomorrow (Tuesday November 20th, 2018) to decide which of their Rule 5-eligible players will be added to the 40-Man roster to protect them from selection in this winter’s Rule 5 Draft, which takes place at the close of the Winter Meetings on December 13th.
As MLB.com’s write-up on the Rule 5 Draft explains, players who are available for selection include those, “... signed when they were 19 or older [who] have played in professional baseball for four years ... [and] players who were signed at 18 and have played for five years.”