Before doing this stage make sure the following is true:
#companybasecore and mascore are clean core tables...They should be 1:1 on themselves. That means 1 key should match to one row in each respective table. See *[Cleaning the Companybase table] *[Cleaning mas table] for instructions
#You've done name based matching on the keys in companybasecore and mascore and cleaned up the matcher output file. See [[#Name Based Matching companybase keys to mas keys|Name Based Matching companybase keys to mas keys]] and [[Fixing Errors in the Matcher Output for portco and mas]]
==Name Based Matching companybase keys to ipo keys==