Filter to add hostname to links

[JJoe]

siamesecat Wrote:Since the link being fixed lacks a protocol and a hostname, why would $URL
find any match?

$URL checks the Page's URL. It's like a Filter's "URL Match".
$URL((http(s|)://)\1*) should always match. \1 will contain the protocol.

siamesecat Wrote:What <BASE*> tag?
The page for which I made the filter has no <BASE> tag on it.
None of my filters does anything to <BASE> tags.

How could I know without asking?

HTH