Webtag Applicability

From Cumulus Wiki

Full information about Web tags can be seen on the linked page. The list of web tags there attempts to identify which web tags can be used whatever release of Cumulus you are running.

The following text used to be on that page, but to simplify that page has now been moved here.


A note of caution

Given how often a new release alters either what web tags are available or what parameters can be used with particular web tags, it is possible the tables on the linked page do not list all web tags at any version, and the tables can't say which modifiers are available at your version.

Beta Builds of Cumulus

Cumulus Version 1 SpecificThe additional webtags page was created to hold web tags that were not yet available in any Cumulus 1 formal release, but were available in any Beta version that was under development.

Badge vMx.pngWhen development of Cumulus 1 ceased, Cumulus MX was available as a beta. At that time, this article continued to describe web tags available in the final release of Cumulus 1 (builds 1099, 1100, 1101, 1099.1, and 1099.2). Because the output parameters were different for MX, all the MX web tag information was in beta web tags article. That was fine in early beta versions of MX because they supported only a small subset of the web tags available for Cumulus 1.


However, as MX development continued more and more web tags were available and maintaining two articles, one for each flavour of Cumulus was impossible. Therefore, MX users had to look at two pages, some of their web tags were in this article some were in that article. Confusingly, some web tags were in both articles, because the parameters that could be used with those tags were increased in MX, so the additional parameters were only shown in the beta article, an example was when the moon web tags had parameters added to control the output from build 3047, these were added to the Beta article.

When Mark Crossley brought MX out of Beta, all the web tags that were on that page were moved into this article, and it was made clear which flavours each web tag was available in (excluding Cumulus 2).

The developer of MX new releases normally shares a new version of MX first as beta by sending the distribution in an email to a number of Cumulus users. They respond by email, with the intension any issues can be ironed out before the distribution is made available as a public release. Given the number of weather station types supported and the complexity of options for using Cumulus, this does not always ensure all ways in which MX can be used are tested, especially as the Cumulus Users given the beta test zip might not use all the features that have been modified in a particular development.

Although such releases often add additional web tags, any additional web tags are currently being entered into this article and no new MX web tags had been added to beta article since that move of the earlier ones into this article.

Cumulus MX

Badge vMx.pngThis badge is used to highlight text that applies to Cumulus 3 (MX) for any release with version numbers 3.0.0 to 3.9.7 ONLY.

  • In many cases, it highlights web tags that are not available in Cumulus 1
  • Use of this badge does not mean that all builds of MX are able to use this web tag
    • Web tags can only be used with template files (Steve Loft names these files in format "xxxxxxT.htm") and none are provided in MX release 3.10.1 or later.
    • Some attempt has been made to indicate either which MX build introduced individual tags, or from which build the web tag started giving the correct response (where earlier builds reported incorrect values for that web tag in some cases).
  • You can, even with latest MX release, create a template file using web tags, as mentioned elsewhere on this page, and fully described on the Customised templates page.
  • MX will raise an error:
    • for any web tag it does not recognise at the version you are running
    • for any input parameter that the token parser is unable to recognise
  • MX treats output parameters differently:
    • any output parameter that it does not recognise at all, is ignored
    • any output parameter in a web tag that does not accept output parameters is also ignored
    • any output parameter in a web tag that does accept output parameters, where the supplied parameter is inconsistent with the content of the web tag, is reported as an error by the token parser
    • an output parameter that specifies only part of the standard output may be reported as an error because of single character rules (for example a tag that reports a time cannot understand format=H, amongst the acceptable formats are format=%H for just hour and format=H:mm for hour and minutes but not seconds.
    • any output parameter that contains incorrectly formatted characters in that output parameter will be treated as an error by the token parser (a common mistake is forgetting spaces are expected to be included with other literal characters by the MX token parser)
    • if you use valid parameters but the wrong parameters, you are likely to be confused by the output (the most common cases result in seeing minutes where a month is wanted, or there is a misunderstanding of the concept where the same character has different meanings when on its own and when with other characters).


Cumulus MX provides many, but not all web tags that were available in Cumulus 1.

MX adds many more web tags, mostly in support of new weather stations or new sensors.

When MX is processing web tags and finds one it cannot understand, a "*** web tag error - see MXdiags file ***" message will appear in the engine console, and the diagnostic file will include something like this, be aware a "token" parser is used to evaluate web tags:

Web tag error
Exception: i=8998 len=106297
inputText.Length=106297
token=<#daylightlength format=H>

This particular error is that when you use a single output format character it does not have same meaning as when there are multiple characters, correct this particular web tag to:

<#daylightlength format=%H>

Please note that where this article makes reference to other pages in the Wiki, the information shown there might be specific to Cumulus 1, as there are differences between the user interface for Cumulus 1 and MX flavours of this software, and the Wiki was originally written before MX existed, so not all pages have been updated.

Cumulus 2

Cumulus 2 is no longer available, it never did any web page generation, so even if you happen to have installed Cumulus 2 from when it was available, there are no web tags it supports.


Original (legacy) Cumulus software

Badge v1.pngThis badge is used to highlight text that applies to Cumulus 1.

  • Use of this badge does NOT mean that all builds of Cumulus 1 are able to use the web tag.
  • There are gaps in the Cumulus 1 documentation, and so it is not usual for the table entry to indicate when a particular web tags started to be available
  • If you are using the final version of Cumulus 1, then the text highlighted by that badge does apply to you.
  • In general, Cumulus 1 will silently ignore any web tag it does not recognise. This means that you might see the raw

web tag remaining after processing, or you might see nothing where the web tag was prior to processing. It also means that if you try to do a numeric calculation on a web tag that Cumulus 1 does not recognise, the calculation will fail, but you might not see an error message.

When Cumulus 1 is processing web tags, it tends to ignore any it cannot understand, so look for gaps in your web pages to find errors.