Writer: introductory text is required here.

#!language = language_ID
#!module = module_name
#!version = version
#!category = category_ID

# comment
message_ID1 {%s:msg}
message_ID2 {%s:msg}
message_ID3 {%s:msg}

# comment
message_ID4 {%s:msg}
message_ID5 {%s:msg}
...