The name was actually "CHRISTMA EXEC" because the IBM VM systems originally required file names to be formatted as 8+space+8 characters. Additionally, IBM required REXX script files to have a file type of "EXEC". The name is sometimes written as "CHRISTMAS EXEC" (adding a 9th character) to make the name more readable.
The original title was "CHRISTMAS EXEC," stemming from the necessity for file names to adhere to an 8-character format plus 8 spaces within IBM's VM systems. Furthermore, REXX scripts required a specific "EXEC" classification.