The NFL allows vets to participate in only one minicamp unless there's a new head coach in the picture (the Giants vets are already whining about Coughlin's extra "voluntary" minicamps).
This weekend is NFL 101 for the Texans rooks and 1st year players. The full squad minicamp is June 14-16.
From the CBA:
Section 1. Number: Each League Year each Club may hold a maximum of one mandatory minicamp for veteran players. If a Club hires a new head coach after the end of the regular season, that Club may hold two additional voluntary minicamps for veteran players. There is no limitation on the number of minicamps a Club may hold for rookie players.
Section 2. Length: No minicamp may exceed three days in length, plus one day for physical examinations. If possible, minicamps should be scheduled for weekends and not in conflict with previously scheduled meetings of the NFLPA Board of Reps or the annual NFLPA convention.
Section 3. Expenses: Any veteran player who attends a minicamp will receive meal allowances in accordance with Article XXXIX (Meal Allowance), Section 1 of this Agreement, plus all travel expenses to and from the camp, plus per diem payments at the rate provided in Article XXXVII (Salaries), Section 4 of this Agreement. In addition, the Club will provide housing at minicamps for players coming from out‑of‑town.
Section 4. Contact: There will be no contact work (e.g., live blocking, tackling, pass rushing, bump‑and‑run) or use of pads (helmets permitted) at minicamps.
Section 5. Injuries: Any player injured in a Clubs minicamp will be protected in the same manner as if injured during the Clubs pre‑season training camp.