The spelling of the word "RRE" may seem unusual, but it is simply an example of a cluster of the letter "r". In IPA phonetic transcription, it would be written as /rɛr/. The double "r" in this case indicates that the "r" sound is elongated or emphasized. This type of cluster is commonly found in words such as "mirror" and "terror". While it may take some practice to pronounce, understanding the IPA transcription can help with proper spelling and pronunciation.