Note 4 - Stock-based Compensation	9 Months Ended
Note 4 - Stock-based Compensation	Jan. 31, 2015
Notes to Financial Statements
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	4 . STOCK-BASED COMPENSATION During the nine months ended January 31, 2015, options to purchase 276,800 shares of common stock were granted (weighted average exercise price of $17.84 per share), options to purchase 36,700 shares were exercised (weighted average exercise price of $3.92 per share) and options to purchase 7,800 shares were cancelled (weighted average exercise price of $17.35). At January 31, 2015, options to purchase 636,655 shares (weighted average exercise price of $11.17 per share) were outstanding and stock-based awards to purchase 2,769,089 shares of common stock were available for grant.

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

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