Is the rule for 50% cash availability also required for selling options?

Is the requirement of 50% cash balance, also applicable while selling options against pledged equity. if yes, is the same uniform across all brokerages or unique to Zerodha.

For shorting options, like futures margin is required. SEBI mandates that 50% of margin has to come in cash. So yeah, required for option selling, and yes across all brokerages.