You maybe right. I could not find the information in the documentation where it is mentioned that the end of line character for a single line expression is '-' character.
I did see the following in OLAP DML documentation.
IF...THEN...ELSE command is documented in OLAP DML Reference Guide: http://docs.oracle.com/cd/E11882_01/olap.112/e17122/dml_commands_2005.htm
+"When IF is used as an expression, the THEN and ELSE keywords must be on the same line as IF. When IF is used as a command, THEN and ELSE must be on separate lines."+
On webpage: http://docs.oracle.com/cd/E11882_01/olap.112/e17122/dml_expression.htm#BABGJIIJ
example 2-4 shows the following: testprogram = IF testtype EQ 0 - THEN 'program0' - ELSE IF testtype EQ 1 - THEN 'program1' - ELSE IF testtype EQ 2 OR testtype EQ 3 - THEN 'program2' ELSE NA