diff --git a/oca-file/src/ocafile.pest b/oca-file/src/ocafile.pest
index b7b706c..0b5dc42 100644
--- a/oca-file/src/ocafile.pest
+++ b/oca-file/src/ocafile.pest
@@ -162,7 +162,7 @@ meta = { ^"meta" ~ arg_ws ~ lang ~  arg_ws ~ props_key ~ prop_key_pairs }
 information = {^"information" ~ arg_ws ~ lang ~ arg_ws ~ attrs_key ~ attr_key_pairs}
 character_encoding = {^"character_encoding" ~ arg_ws ~ attrs_key ~ attr_key_pairs}
 character_encoding_props = {^"character_encoding" ~ arg_ws ~ props_key ~ prop_key_pairs}
-format = {^"format" ~ arg_ws ~ attrs_key? ~ attr_key_pairs}
+format = {^"format" ~ arg_ws ~ attrs_key ~ attr_key_pairs}
 conformance = {^"conformance" ~ arg_ws ~ attrs_key ~ attr_key_pairs}
 conditional = {^"condition" ~ arg_ws ~ attrs_key ~ attr_key_pairs}
 cardinality = {^"cardinality" ~ arg_ws ~ attrs_key ~ attr_key_pairs}