Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Thu, 8 Sep 2016 13:48:43 -0500

On 09/08, Ralph Lange wrote:
> Hi Lewis, 
> 
> Please remember that in EPICS context, record and PV are not the same. 
> 
> MyRecord.SCAN is a perfectly valid PV name, containing a dot. 

Hi, Ralph!

Ah, I see!  Yes, sorry about that!  Thanks!

> Chapter 6.4.11 in your AppDevGuide describes the record instance, and
> correctly mentions the allowed characters for record names.

Hmm, in the guide on the EPICS website for 3.14.12 I think it's 6.14.2,
but yes, I do see what you're talking about:

  record_name 

  The record name. This must be composed of the following characters:

    a-z A-Z 0-9 _ - + : [ ] < > ;

And obviously there's no dot in that list.  Thanks for that.

Back on legal characters for a PV name, is it true that a PV name can
have no more than one dot in it (i.e. the dot separating the record name
from the field name)?

If true, then a PV name cannot start with a dot since that would mean a
zero-length record name which is illegal, right?

What about ending with a dot--can a PV name end with a dot?  Is that
interpreted as an empty field which defaults to VAL, or is a trailing
dot illegal?

Would a developer be open to a patch from me to the documentation to
further clarify the statement about legal PV name characters in section
6.3.2, Unquoted Strings, in light of the above questions?

Thanks,

Lewis

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System