Opened 4 years ago

Closed 4 years ago

#189 closed defect (fixed)

Two concerns on syntax tree

Reported by: Carsten Owned by:
Priority: minor Milestone: Version 2.1
Component: unit definitions Keywords:
Cc:

Description

I have 2 concerns about the complete syntax tree outlined in Exhibit 1 here: http://unitsofmeasure.org/ucum.html

First

This definition of <term> must be wrong since it points to itself as the last option. Instead, the third option ought to be <component> right?

<term> ::= <term>“.”<component> | <term>“/”<component> | <term>

Suggested Fix:

<term> ::= <term>“.”<component> | <term>“/”<component> | <component>

Second

For the <simple-unit> rule, this seems to suggest that any <PREFIX-SYMBOL> may be used with any <ATOM-SYMBOL>, but that is not the case since only the SI units may use the prefixes right?

<simple-unit> ::= <ATOM-SYMBOL> | <PREFIX-SYMBOL><ATOM-SYMBOL>

Suggested Fix:

<simple-unit> ::= <ATOM-SYMBOL> | <PREFIX-SYMBOL><SI ATOM-SYMBOL>

<ATOM-SYMBOL> ::= <SI ATOM-SYMBOL> | <NON-SI ATOM-SYMBOL>

Change History (1)

comment:1 Changed 4 years ago by Gunther Schadow

Component: helpunit definitions
Milestone: Version 2.1
Resolution: fixed
Status: newclosed

First: yes you seem to be right. Fixed.

Second: we did not intend to include the disallowability of prefix-atom pairing in this syntax. I have added a bracket <ATOM-SYMBOL[metric]> to indicate this as a constraint, referring to our "metric" property (as the combinability with a prefix applies to units other than SI).

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