This blog is written in English. Therefore the letters used are normally restricted to A to Z.
The English alphabet is one of many alphabets using Latin (or Roman) letters. Other alphabets like the Russian uses Cyrillic letters. Then there are other script systems in the world which besides alphabets are abjads, abugidas, syllabic scripts and symbol scripts. Learn more about these in the post Script Systems.
The letter Æ is a combined AE and is pronounced in English as the first letter in Edmund and Edward.
Today Æ exists in a few alphabets: The Danish/Norwegian, the Faroese and the Icelandic. People and places from the corresponding Viking territories may have the letter Æ/æ as part of the string. For example the home of Microsoft Dynamics AX and NAV is the town Vedbæk north of Copenhagen. When represented in the English alphabet the town name will be Vedbaek.
So Vedbæk and Vedbaek should be a 100% match when doing data matching. And so should Vedbæk and Vedb%C%A6k when systems are as bad as Æthelred the Unready was in handling the Vikings.
And oh, Æthelred wasn’t actually unready. He was unræd meaning bad-counseled.