Players selected in the MLB First-Year Player Draft (MLB Rule 4 Draft) are placed on a club's Negotiation List.
In most cases, a player selected by a club in the Rule 4 Draft will remain on the club's Negotiation List until either the player signs, or until 5:00 PM (EDT) on the Friday that falls during the week July 12-18 (whichever comes first), and if a club does not sign a Rule 4 Draft pick by the deadline, the player is removed from the club's Negotiation List and becomes eligible for selection again in the next Rule 4 Draft in which the player would be eligible for selection. The exception to this rule is any college senior with no baseball eligibility left. This class of player remains on the club's Negotiation List until the player signs or until one week prior to the next Rule 4 Draft (whichever comes first).
Also, any player eligible for selection in the Rule 4 Draft who is not drafted ("Non-Drafted Free-Agent" or "NDFA") can sign with any club after the conclusion of the draft any time up until one week prior to the next Rule 4 Draft, unless and until the NDFA enrolls in a junior college or four-year college, in which case MLB Rule 4 Draft eligibility requirements apply.
A player selected in the MLB Rule 4 Draft or a Rule 4 eligible NDFA cannot be signed to a Major League contract.
A player selected in the MLB Rule 4 Draft or a Rule 4 eligible NDFA can be "Signed for Future Service" (contract is for the following season) if the player signs a contract after July 1st.
A club is not permitted to select a player in the Rule 4 Draft two years in a row, unless the player gives his approval in advance.
CUBS NEGOTIATION LIST (updated 7-12-2013):
Josh McCauley, RHP (Shepherd U.) - SR - NO COLLEGE ELIGIBILITY LEFT
Tyler Sciacca, 2B (Villanova) - SR - NO COLLEGE ELIGIBILITY LEFT