Opened 6 years ago
Closed 6 years ago
#189 closed defect (fixed)
Two concerns on syntax tree
Reported by: | Carsten | Owned by: | |
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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 6 years ago by
Component: | help → unit definitions |
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Milestone: | → Version 2.1 |
Resolution: | → fixed |
Status: | new → closed |
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).