Design
1.Small and compact
2.Modern
3.Digital read out
4.3/4", 1" 5/4"available, 
5.Valve be weatherproof as it can be installed outside and inside
6.12 volt power, many cases may be installed hundred feet or more from a power supply.  (so will need to be able to carry the power supply thru standard low voltage irrigation wire) Battery backup

Functions
1.Can be programmed by city administrator to open odd/even days, on certain days of the week, for example only open on Tuesdays or Tue and Sat.
2.Can be programmed to know the calendar for many years in advance (leap year, daylight savings)
3.Programmable to open at set periods of time on given dates.  For example open from 6pm-10am.
4.Tamper resistant.  If power disrupted valve closes.
5.Uses RF-IC card to program, or can be programmed by remote control.
6.Also have functions for the master card as discussed earlier.