This question already has an answer here:

The model was exported as a/an XML file.

an XML file sounds better to me – is it exception like an hour?

marked as duplicate by jejorda2, Edwin Ashworth, Cascabel, John Lawler, choster Feb 15 '17 at 17:24

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • 1
    The pronunciation of "XML" begins with a vowel, so use "an." – jejorda2 Feb 15 '17 at 16:38
  • 1
    The choice between 'a' and 'an' is not grammatically based but facilitation-of-reading based. – Edwin Ashworth Feb 15 '17 at 16:41

Use AN before any non-consonant sound. That includes H in HERB (unless you don't pronounce it "erb") but not HISTORY. XML is pronounced "Ex Em El," so that takes AN, not A.

Some might say the rule is AN only before vowels, but most style guides refer to the vowel-like sound of the word following the article, not the actual spelling. There are a lot of very complex linguistic concepts about word and sound pronunciation, so there are precise ways to explain this, but it's basically about having a hard consonant vs. vowel sound.

  • Please check obvious candidates for duplicate status before answering. – Edwin Ashworth Feb 16 '17 at 1:54

The model was exported as an XML file.

As "x" is pronounced as 'eks" , with an initial vowel, "an" is proper. [grammar) 1

However, English has no "Academy" to decide the issue, so, using "a" before an "X" cannot be said to be wrong.

Not the answer you're looking for? Browse other questions tagged or ask your own question.