Naming Conventions

POSC has established conventions for naming data modeling objects, including entities, attributes, rules, and schemas. Names shall be referenced by application programs using the application program interface.

The model names for schemas, entities, attributes, defined types, and rules conform to the following rules and guidelines.

Content Rules

E&P Data Model names are restricted to use the 26 lowercase English alphabet characters, number characters 0-9, and underscore.
Special characters, including brackets, quotation marks, question marks, slashes, commas, stops and hyphens are not allowed in a name.
Component words that form a name should be separated by an underscore.
Names shall not start with a number or an underscore character.
Names for schemas, defined types, and rules are variable length strings of a maximum width of 40 characters.
Names for entities and attributes are variable length strings of a maximum width of 30 characters.
Complete names shall not be the same as any EXPRESS language reserved phrases, or as any SQL3 reserved words.

Content Guidelines

A name should be in a singular form.
Do not use prepositions, conjunctions, articles, "and," "or," or other superfluous words in a name.
Avoid redundant qualifier words (redundant because they appear elsewhere in the context).
The position of a qualifier word in a name should depend on its significance to the name, i.e., place the most significant qualifier word in the front.

Standard Prefixes

The model uses some standard name prefixes to aid understanding. These are:

Pty - for names of all property subtypes.
Ndt - for names of all named defined types.
Ref - for names of most reference entities.

Name Scope

Names of entities, attributes and rules are unique within some scope. The scope rules are those of EXPRESS:

Entity names shall be unique within a schema.
Attribute names shall be unique within the scope of the parent entity, which includes all of its subtypes.
Local rule names shall be unique within the scope of the parent entity.
Global rule names shall be unique within the scope of the schema.

Reserved Words

Epicentre names cannot coincide with any of the reserved words of EXPRESS or of SQL3.

The list of reserved words and phrases is given below. They are taken from Tables 1, 2, 3, 4, and 5 of ISO 10303-11, and ANSI X3H2-93-004.

EXPRESS Reserved Phrase List
abs abstract acos aggregate alias and andor array as asin atan bag begin binary blength boolean by case const_e constant context cos derive div	else end end_alias end_case end_constant end_context end_entity end_function end_if end_local end_model end_procedure end_repeat end_rule end_schema end_type entity enumeration escape exists exp false fixed for	format from function generic hibound hiindex if in insert integer inverse length like list lobound local log log10 log2 logical loindex mod model not	number nvl odd of oneof optional or otherwise pi procedure query real reference remove repeat return rolesof rule schema select self set sin sizeof	skip sqrt string subtype supertype tan then to true type typeof unique unknown until use usedin value value_in value_unique var where while xor

SQL3 Reserved Words List
absolute action actor add after alias all allocate alter and any are as asc assertion async at authorization avg before begin between bit bit_length boolean both breadth by call cascade cascaded case cast catalog char character char_length character_length check class close coalesce collate collation column commit completion connect connection constraint constraints constructor continue convert corresponding count create cross current current_date current_time current_timestamp current_user cursor cycle data date day deallocate dec decimal declare default deferrable deferred delete	dept deref desc describe descriptor destroy destructor dictionary diagnostics disconnect domain double drop each else elseif end end_exec equals escape except exception exec execute exists external extract false fetch first float for foreign found from full function general get global go goto grant group having hour identity if ignore immediate in indicator initially inner input insensitive insert int integer intersect interval into is isolation join key language last leading leave left less level like limit local	loop lower make match max min minute modify module month names national natural nchar new next no none not null nullif numeric octet_length of off oid old on only open operation operators option or order others outer output overlaps pad parameters partial pendant position precision preorder prepare preserve primary prior private privileges procedure protected public read real recursive ref references referencing relative remove representation resignal restrict return returns revoke right role rollback routine row rows savepoint	schema scroll search second seconds section select sensitive sequence session session_user set signal similar size smallint some space sql sqlcode sqlerror sqlexception sqlstate sqlwarning structure substring sum system_user table template temporary test than then there time timestamp timezone_hour timezone_minute to trailing transaction translate translation trigger trim true tuple type under union unique unknown update upper usage user using value values varchar variable varying view virtual visible wait when whenever where while with without work write year zone