SQL & PL/SQL :: Regex Validation?

I have data stored in the format 01.01 , 01.02,02.03 in one field of table , i dont want my user to deviate from this coding by not typing like 0001.01 or anything othen than above format , how can i prevent this.

CREATE TABLE OM_AIC_SALES_CODES ( SALE_CODE VARCHAR2(6),SALE_DESC VARCHAR2(240),SALE_MIN_WT NUMBER, SALE_MAX_WT NUMBER)
insert into om_aic_sales_codes ( SALE_CODE ,SALE_DESC ,SALE_MIN_WT , SALE_MAX_WT ) values ('01.01','Extra Light <= 30 kg/m',NULL,NULL);
insert into om_aic_sales_codes ( SALE_CODE ,SALE_DESC ,SALE_MIN_WT , SALE_MAX_WT ) values ('01.02','Light >30 <=60 kg/m',NULL,NULL);

--i dont want the following inserts to happen or invalid inserts.

insert into om_aic_sales_codes ( SALE_CODE ,SALE_DESC ,SALE_MIN_WT , SALE_MAX_WT ) values ('01.003','Light >30 <=60 kg/m',NULL,NULL);
insert into om_aic_sales_codes ( SALE_CODE ,SALE_DESC ,SALE_MIN_WT , SALE_MAX_WT ) values ('001.003','Light >30 <=60 kg/m',NULL,NULL);
insert into om_aic_sales_codes ( SALE_CODE ,SALE_DESC ,SALE_MIN_WT , SALE_MAX_WT ) values ('0001','Light >30 <=60 kg/m',NULL,NULL);