The question of how to give permalinks to specific posts has been asked on miniBB years ago.

In default version, links to certain posts provided under '#' sign appearing above or near each post, and then the whole hyperlink to such message will consist of the full Topic's URL + '#msgID' anchor at the end of it, supposing the browser to redirect to such a message directly, if this URL is pasted somewhere.

It absolutely works for the very first messages in each Topic, but as soon the Topic grows and is split by pages, there could happen that some linked messages could be moved from page A to page B - for example, in the case of deleting some messages, or moving them to another Topic. Then the direct links, which are using certain page numbers, will lead to nowhere and could look quite confusing, not allowing to find the certain linked message. This, in some terms, is bad for SEO.

Also, in the case of mod-rewritten URLs, if URL-parsing function is changed for some reason (new convertion rules added), miniBB will try to redirect to the most proper URL, and it will anyway lead to the 301-redirection mechanism.

The new free Advanced Anchors add-on uses an external specific script (so called "message locator" - msg.php), which is substituted instead of the direct Topic links under '#' sign. Linking to this script anywhere on the forum or external web pages, will always provide valid links to certain messages. This script will try to locate a message in both live or optionally archived forum tables; also it uses the most proper HTTP protocol headers, providing either 301 (for found messages) either 410 report codes, which are very useful for search engines like Google and SEO overall.

An extra addition to this forum allows to install a set of special BB-codes, which will produce specifically named anchors; they could be used in large starting topic texts to refer directly to the exact portions of such texts. Message locator supports direct moving to such anchors as well - read instructions in README.txt for proper usage. This feature is mostly useful for professional writers, building the most properly hyperlinked paragraphs. I've used it in some posts of the 2014 blogs.

This add-on is one of the rare extras which I also preferred to install here on miniBB forums, so you could test it right here. It's very useful for content-oriented forums, or if they related to knowledge base. Also, if you simply take care of your forum members, my recommendation is to install this add-on for bringing less confusion on the clients' end.

Take care, and enjoy a simple life :)