UML25 — Notation: Real

The wording for Real allows '000.9' and '.9' as valid numbers. Permitting redundant leading zeroes is undesirable given the usage of leading zero as octal in some languages. Permitting the omission of a leading zero is also undesirable. The equivalent wording in OCL 2.3 is better but not perfect. "A real literal consists of an integer part, a fractional part and an exponent part. The exponent part consists of either the letter 'e' or 'E', followed optionally by a '' or '-' letter followed by an exponent integer part. Each integer part consists of a sequence of at least one of the decimal digit characters. The fractional part consists of the letter '.' followed by a sequence of at least one of the decimal digit characters. Either the fraction part or the exponent part may be missing but not both."UML and OCL should have compatible definitions.

What is the concrete syntax for +/- infinity?

Both “000.9” and “+.9” are numerically correct representations of Reals. As a modeling language, it seems that UML
should allow the same flexibility in literal notation as typical mathematical convention would allow. If a modeler wants
to write “.9”, it doesn’t seem necessary for UML tools to be required to prevent this. There is no syntax for +/- infinity,
since these are not values included in the mathematical range of real numbers. Certain floating point implementations
may include such values, but the concept of Real in UML has intentionally been kept independent of implementation
standards and, instead, kept as close to the mathematical conception of real numbers as possible (similarly to how
Integer has previously been handled in UML).
Disposition: Closed - No Change