A cap hold called an "incomplete roster charge" if the team has fewer than 12 players (players under contract, free agents included in team salary, players given offer sheets, and first round draft picks). This charge is equal to the rookie minimum salary for each player fewer than 12. For example, if there are 11 players included in team salary, then an amount equal to the rookie minimum salary is added to the team salary (5); if the roster is completely empty, then 12 times the rookie minimum salary is added to the team salary. This charge only applies during the offseason.
I read that to mean a teams needs to account for 11 roster cap holds/charges before signing a FA. I then see the link to Footnote 5 which states:
Since teams are required to have at least 13 players on their rosters (see question number 79), the roster charge reserves a minimum amount of cap space to sign 13 players. For example, if a team has 11 players on its roster, the roster charge reserves cap space to sign the team's 13th player, and the remainder can be used to sign the 12th player.
The footnote makes it sound like in order to sign a FA with cap space, you need to have 12 roster cap holds/charges before signing the FA.
There must be something in the fine print I am missing because I cannot resolve those two against each other. Additionally, I have read articles posted in the past couple of weeks that work under both assumptions.
http://www.cbafaq.com/salarycap.htm#Q14