7.5 Field Attributes

BML-related field attributes are added as additional attributes to regular fields in the fields table (see Fields Data Structure). They describe properties of the particular field they are attached to. The attributes are as follows:

• FieldModifers - BML related modifiers of a field (e.g., non_null/nullable etc).

7.5.1 FieldModifiers Attribute

The FieldModifiers attribute contains the BML related modifiers of the field. It has the following structure:

     FieldModifiers_attribute {
       u2 attribute_name_index;
       u4 attribute_length;
       u4 BML_flags;
     }

The meaning of the fields is as follows:

• attribute_name_index - index in the primary constant pool of the attribute name (org.bmlspecs.FieldModifiers)
• attribute_length - length in bytes of the whole structure
• BML_flags - the flags that are set for the field. The allowed flags are BML_NON_NULL, BML_NULLABLE, BML_SPEC_PUBLIC, BML_SPEC_PROTECTED, BML_PEER, BML_REP, BML_READONLY, BML_ELEM_PEER, BML_ELEM_READONLY. All other flags must be cleared. Only one of BML_NON_NULL, BML_NULLABLE can be set. Only one of BML_SPEC_PUBLIC, BML_SPEC_PROTECTED can be set. Only one of BML_PEER, BML_REP, BML_READONLY can be set.. Only one of BML_ELEM_PEER, BML_ELEM_READONLY can be set only if one of BML_PEER, BML_REP, BML_READONLY is set and the field is an array.

There should be no more than one FieldModifiers attribute per field. In case there are more than one the tools should use the first one in the binary representation.