The tags and seem to be used pretty interchangeably on StackOverflow. In most, if not all cases, I feel that is how the question should be tagged.

In many cases, questions are tagged as both.

Could the two tags be merged into ?

8 Answers 8


The semantic distinction between "XSL" and "XSLT" may be useful in some contexts, but SO's tag taxonomy isn't one of them.

I browsed through the top 30 or so questions tagged with "xsl" to see if I could find one that was about XSL and not XSLT, and couldn't. In all cases, the questioner was using "XSL" and "XSLT" interchangeably. This shouldn't be terribly surprising; people to whom the distinction between the two is significant don't ask a lot of questions about either of them.

There are times when I'm adamant that the proper terminology be used (do not say "nodes" when you mean "elements" in my hearing), but I think that cleaving to this particular distinction, in this particular context, probably does no good and may do a little harm.

  • (+1). As usual Robert knows well what he's speaking about. Sep 6, 2010 at 4:24
  • (+1) Agreed. The majority of XSL questions are for XSLT and it makes sense to merge. Technically, XSL should be merged into XSL-FO, but the typical user does not know/understand the difference between the the XSL* family or the history of the names. Sep 6, 2010 at 11:20

Although XSL can also mean XSL-FO, it's almost always in reference to XSLT, so I think it should be a synonym in absence of any hierarchy of broader-tag/narrower-tag.

  • 1
    Furthermore, almost every tag tagged with XSLT is also tagged with XSL
    – Eric
    Aug 24, 2010 at 9:34
  • 1
    (+1). Everybody, who isn't aware of the "xslt" tag and asks his (in reality xslt) question under "xsl" has now to wait a lot longer than the people with questions tagged "xslt" in order for his question to be noticed by the experts. The current tag separation is hurting such users. Sep 6, 2010 at 4:23

From http://www.w3.org/Style/XSL/

XSL is a family of recommendations for defining XML document transformation and presentation. It consists of three parts:

  • XSL Transformations (XSLT) a language for transforming XML
  • the XML Path Language (XPath) an expression language used by XSLT to access or refer to parts of an XML document. (XPath is also used by the XML Linking specification)
  • XSL Formatting Objects (XSL-FO) an XML vocabulary for specifying formatting semantics

Then, unless people is asking about this family relationship, history, etc., the question is erroneously tagged.

Since there is no feature that automatically add a label to another, where it can be corrected if appropriate, I think it should stay this synonym.

  • 2
    I upvoted you on this, @ALejandro. We know too well, how it hurts to try to find XSLT questions under two different tags. This must be corrected. Sep 6, 2010 at 4:25

XSL and XSLT are two separate things. XSL is "Extensible Stylesheet Language", while XSLT is specifically "XSL Transforms". People can (and often do, on SO) use XSL alone to refer to XSLT, but it can also be used for XSL-FO (XSL Formatting Objects).

Think of it like how we have a separate C# tag and a C#4.0 tag. That kind of relationship isn't so much ambiguity, as it is a superclass.

Keeping them separate, I think, would be preferable.

  • 2
    Thank you for this great academic treatment of the question. The only "minor" problem with it is we need to be practical and the synonym system is here to be of practical use -- not the reverse. Sep 6, 2010 at 4:20
  • 1
    I tend to agree that what we observe in practical use of these tags -- the actual real world data on the site -- should inform our decision here most of all Sep 6, 2010 at 6:39
  • I think the difference - regarding questions on SO - between [xsl-fo] and [xslt] is a very subtle one (XSL-FO questions usually involve XSLT and SO users won't get the difference when asking). Besides, having a C# and a C# 4.0 tag is no other than having an XSLT and XSLT 2.0 tag. As others said, XSL(T) is already a niche topic on SO and I don't think there is additional benefit in further splitting up things.
    – 0xA3
    Sep 6, 2010 at 9:19

We must be practical. We are not academic writers preparing a scientific tome on the origin and meanings of words in a particular topic-world.

The vast majority (much more than 90%) of questions tagged "xsl" are xslt questions. People, who ask xsl-fo questions typically tag them "xsl-fo" and such questions happen to be quite rare.

So, we have a practical need here -- in order to better serve all our users, who are not aware of the subtle problem that xsl isn't the same as xslt, and whose questions may stay unnoticed for a prolonged time because xslt experts sometimes have a lot of questions tagged "xslt", it is really useful if at SO "xsl" be permanently established as a synonym of "xslt".

Let's avoid all the etimological, philosophical and historical aspects and just be practical.


I've been pondering if I should ask this exact question for a long time myself. In fact, I was the one who suggested the tag synonym.

I think that most people that use the [xsl] tag do so because that's the file extension and the XML namespace prefix. In reality they mean [xslt].

For me, these two tags are synonymous and should be merged into [xslt].

The finer points of [xsl] vs. [xslt] vs. [xsl-fo] are irrelevant to a Q and A site like this one, and just add confusion to something that already is a niche topic. Keeping [xsl-fo] as a separate tag should suffice.


Since that all the tag leaders agreed that it makes sense to have this synonym in place. I went ahead and created the synonym AND merged the tags.

In the vast majority of cases users mean xslt when they tag stuff xsl, hence I placed this synonym and merged.


These two are almost as interchangeable as C and C++...


  • 1
    To the downvoter: Meaning they are not. Get your irony detector checked.
    – MPelletier
    Sep 2, 2010 at 19:49
  • I also received a downvote at around the same time, so it could very well be that someone simply disagrees that they are not interchangeable. Likewise, both pro-syn answers got upvoted.
    – Grace Note StaffMod
    Sep 2, 2010 at 19:52
  • 2
    The vast majority of questions asked under "xsl" are xslt questions. The synonym system must reflect this, or it is not just unusable, but harmful. Also, it is wise not to interfere in subject-worlds in which you aren't an expert. I understand XSLT and this is why I am writing this. I would never interfere in a topic about security or wine. Sep 6, 2010 at 4:30
  • @Dimitre, I agree that the synonym system must be practical before theoretical. However, as an expert, you must agree that the misunderstanding in that field is a bit of a shame, no?
    – MPelletier
    Sep 6, 2010 at 15:18

Not the answer you're looking for? Browse other questions tagged .