AMPscript ELSEIF statement evaluating incorrectly

Question

I have an ELSEIF AMPscript statement that looks like this:

<script runat=server language=ampscript>

var @code, @templateName

set @code = 'M200'

if @code == 'E001' then
   set @templateName = 'Letter A'
elseif @code == 'M001'
     or @code == 'M014'
     or @code == 'M400' then
   set @templateName = 'Letter B'
elseif @code == 'M002'
     or @code == 'M500' then
   set @templateName = 'Letter C'
elseif @code == 'M003' 
     or @code == 'M200' then
   set @templateName = 'Letter D'
elseif  @code == 'M004'
     or @code == 'M005'
     or @code == 'M006'
     or @code == 'M007'
     or @code == 'M008'
     or @code == 'M009'
     or @code == 'M010'
     or @code == 'M011'
     or @code == 'M012'
     or @code == 'M013'
     or @code == 'M600' then
    set @templateName = 'Letter E'
elseif @code == 'M015' then
   set @templateName = 'Letter F'
elseif @code == 'V100' then
   set @templateName ='Letter G'
else
   set @templateName = 'undefined'
endif
</script>

%%=v(@templateName)=%%

I would expect @templateName to return 'Letter D' but it is returning 'Letter E'. Why do you think this is?

Answer 1

I figured it out. I used two space characters after one of my elseif statements for formatting (alignment) purposes:

elseif  @code == 'M004'

If you do this, it appears that the if statement evaluation breaks and returns the incorrect result. As soon as I remove the second space character, it works correctly:

elseif @code == 'M004'