An enum to identify lock types:
SMC_LOCK_T_EX_TAB
SMC_LOCK_T_SH_TAB
SMC_LOCK_T_EX_INT
SMC_LOCK_T_SH_INT
SMC_LOCK_T_EX_PAGE
SMC_LOCK_T_SH_PAGE
SMC_LOCK_T_UP_PAGE