given independently from each other in alphabetical order as defined above with all entity values grouped together in parentheses. Internal mapping is used by default for conformance option 1 when the complex entity instance consists of only one leaf entity. The encoding is similar to the one of a single entity instance with the additional order given by the subtype definition. Mapping of attribute values: Only explicit attributes get mapped. Inverse, Derived and re-declared attributes are not listed since their values can be deduced from the other ones. Unset attribute values are given as "$". Explicit attributes which got re-declared as derived in a subtype are encoded as "*" in the position of the supertype attribute. Mapping of other data types: Enumeration, boolean and logical values are given in capital letters with a leading and trailing dot such as ".TRUE.". String values are given in " ". For characters with a code greater than 126 a special encoding is used. The character sets as defined in ISO 8859 and 10646 are supported. Note that typical 8 (e.g. west European) or 16 (Unicode) bit character sets cannot directly be taken for STEP-file strings. They have to be decoded in a very special way. Integers and real values are used identical to typical programming languages Binary values (bit sequences) are encoded as hexadecimal and surrounded by double quotes, with a leading character indicating the number of unused bits (0, 1, 2, or 3) followed by uppercase hexadecimal encoding of data. It is important to note that the entire binary value is encoded as a single hexadecimal number, with the highest order bits in the first hex character and the lowest order bits in the last one. The elements of aggregates (SET, BAG, LIST, ARRAY) are given in parentheses, separated by ",". Care has to be taken for select data types based on defined data types. Here the name of the defined data type gets mapped too. See also "Mapping of Express to Java" for more details of this. Criticism Possibly the only advantage of STEP files is that they are widely adopted in many CAD software. On the other hand, its format, and specially the EXPRESS has a few disadvantages: the specification is not freely available (you have to pay for it) it is not possible to sequentially read a STEP file. Entities can be in any order and can reference other