When to use hreflang for language and regional URL tags

[onlinesource]

Currently I have a website setup that uses a multi site setup. Within my structure is my .com domain, a .ca one, .co.uk and a .in domain. Each site is essentially an online shop which shares a lot of the same stuff (products, categories, pages, etc), although images and some text have been changed to make it individually geared towards a certain county. In the end, [mystore.au...] is the same as [mystore.au...]

Right now, at the bottom of my site, I have a hyperlinks to all 4 sites and obviously the same list appears at the bottom of every site. In other words, the list says, "see our Canada store, see our Uk store, etc". I know if I just put a repeated list of links on all sites, it would look like link farming to Google. So instead, I have done this:

<link rel="alternate" hreflang="en-AU" href="http://www.mystore.com.au"/>
<link rel="alternate" hreflang="en-CA" href="http://www.mystore.ca"/>
<link rel="alternate" hreflang="en-GB" href="http://www.mystore.co.uk"/>
<link rel="alternate" hreflang="x-default" href="http://www.mystore.com"/>

This should tell Google that although I am linking to each store, each store serves it's own purpose.

My question is, some of my pages and posts have internal links back to my main domain. In other words, let's say I wrote a block about t-shirts and in the blog post I say, "Looking for the best t-shirts, then visit Site-X!" Well, on the .ca store, Site-X links to [mystore.ca,...] on the UK store... the uk domain,etc. Should my url be as simple as <a href="http://www.mystore.ca">Site-X</a> or should I go as far as <a rel="alternate" hreflang="en-CA" href="http://www.mystore.ca">Site-X</a> even for internal linking? I figured most people viewing that hyperlink are already on the .ca site, so there is no need to mention the language or region in the url tag.

Sorry if I this sounds confusing. :)

[lucy24]

Short answer: There's no point in saying "alternate" if you are not, in fact, going to offer alternatives. If, for example, the UK store has no t-shirts section so your UK page offers links to the US and CA pages instead, then there would be some reason for "alternate".

You could include "hreflang" but, again, I don't think it's important unless the target is in a different language than the originating page.

:: detour to pore over HTML5 spec, which leaves me uneasily wondering what, exactly, "palpable content" is ::

This relationship is transitive — that is, if a document links to two other documents with the link type "alternate", then, in addition to implying that those documents are alternative representations of the first document, it is also implying that those two documents are alternative representations of each other.

(Just quoting that because it seems like an awfully verbose way of saying that if A=B and A=C, then B=C.)