Requested feature overview description.
The API endpoint /post/show.xml has no option to return typed tags like /post/index.xml has. The request is to add such an option.

Example:
[1] /post/index.xml?tags=id:6268 returns

[...]<tags>ambiguous_gender anal anal_fingering anthro anus [...]</tags>[...]

[2] /post/index.xml?tags=id:6268&typed_tags=1 returns

[...]<tags>
  <general type="array">
    <tag>cum_in_own_mouth</tag>
    <tag>grey_tail</tag>
    [...]
  </general>
  [...]
</tags>[...]

[3] /post/show.xml?id=6268 returns the same as [1].
[4] /post/show.xml?id=6268&typed_tags=1 also returns the same as [1] but should return the same as [2] instead.

Why would it be useful?
Combined with the fact that /post/index.xml does not return deleted posts (see this bug report for details), there is no reasonably easy way of getting the typed tags of a deleted post.
A possible workaround is to parse the HTML returned by /post/show.html?id=6268 but parsing HTML is a nightmare on its own and it's more work for the server to hand out the responses.

What part(s) of the site page(s) are affected?
The API endpoint /post/show.xml, and the same can be applied to the /post/show.json endpoint as well.

mononatriumglutamat said:
Requested feature overview description.
The API endpoint /post/show.xml has no option to return typed tags like /post/index.xml has. The request is to add such an option.

Example:
[1] /post/index.xml?tags=id:6268 returns

[...]<tags>ambiguous_gender anal anal_fingering anthro anus [...]</tags>[...]

[2] /post/index.xml?tags=id:6268&typed_tags=1 returns

[...]<tags>
  <general type="array">
    <tag>cum_in_own_mouth</tag>
    <tag>grey_tail</tag>
    [...]
  </general>
  [...]
</tags>[...]

[3] /post/show.xml?id=6268 returns the same as [1].
[4] /post/show.xml?id=6268&typed_tags=1 also returns the same as [1] but should return the same as [2] instead.

Why would it be useful?
Combined with the fact that /post/index.xml does not return deleted posts (see this bug report for details), there is no reasonably easy way of getting the typed tags of a deleted post.
A possible workaround is to parse the HTML returned by /post/show.html?id=6268 but parsing HTML is a nightmare on its own and it's more work for the server to hand out the responses.

What part(s) of the site page(s) are affected?
The API endpoint /post/show.xml, and the same can be applied to the /post/show.json endpoint as well.

Was curious about recent site change ... https://e621.net/post/index.xml?tags=id:6268 -> 403's forevermore on *.XML
This example is no longer usable. I don't think it worked anymore, anyways.

403 Access Denied - Oh no!
If you were using a script/program you found to try and download content, it's likely that the script was what resulted in your request being blocked. Have you perhaps tried Grabber instead? It's great, and probably does what you want!
There are a few different reasons that you can run into this message:
You have not updated your application to use the new API urls and response formats. See #1
You are using an outdated program that makes use of bad practices or old API endpoints. See #2
Your applications user agent is incorrectly configured. See #3
Something else, I've checked the above 3 and they don't apply to me. See #4
#1 Outdated API usage
We updated our codebase quite drastically in March 2020. As the result of no shared code between the old and new site, the API changed, both in response format and urls. You need to update your application to use the new API urls and response formats.

If you are making requests to endpoints that are not plurals, then you fall under this category. Please visit the wiki for the most up to date information. Do not use some random "documentation" you found on github, it is out of date and incorrect.

#2 Outdated application
You likely can't resolve this problem yourself, as the application you are using needs to be updated. Please contact the author, or find another, more up to date tool.

#3 Bad User-Agent usage
If you are attempting to use the API you may be seeing this if your user agent is not in line with our user agent policy. The default user agent for many programming languages and libraries have been blocked for abuse. DO NOT USE A BROWSER USER AGENT FOR API TOOLS - YOU WILL GET MANUALLY BLOCKED. You've been warned. Please see the wiki page for the API for additional details.

#4 Something else, probably abusive behavior
If you repeatedly see this message you should stop all access attempts and contact us so that the problem can be resolved.

If none of the above apply to you, then you have likely been blocked manually after review. These blocks DO NOT EXPIRE. You will need to contact us to have it removed.

You can reach us at management (at) e621 (dot) net

Please include your ip address, the time you received this message and what you were doing at the time. We will respond as quickly as possible.