This rule monitors substantial high-value local card transactions with category-based exemptions for established enterprise merchants.

Triggers when:
1. Transaction exceeds AED 400,000
2. Card is locally-issued (UAE)
3. Merchant is NOT categorized as Cat A (Enterprise excluded from this rule)

The category exclusion is significant:
- Cat A merchants have proven track records with high-value legitimate transactions
- Cat B/C/D merchants rarely process transactions at this level legitimately
- Sudden high-value on lower-tier merchant indicates potential:
  * Account compromise
  * Business email compromise fraud
  * Unauthorized employee transactions
  * Money laundering attempt

Transaction placed on HOLD for thorough verification:
- Merchant contact for authorization confirmation
- Review of merchant transaction history
- Validation that amount aligns with business type
- Cardholder verification if necessary