I suspect this is a regression. I am using this test document:
```
@@latex:
\documentclass[margin,11pt]{res} % default is 10 pt
@@
```
and dumped the AST with M-x eval-expression (message "%s" (pp-to-string
(org-element-parse-buffer)))
When using the latest in main (commit b89bc55867d7cb809c379d371d12d409db785154,
Org mode version 9.7-pre (release_N/A-N/A-b89bc5 @
/usr/share/emacs/site-lisp/org/)) the "@@latex:" gets parsed as an export
snippet despite not having a closing "@@" (because the "@@" is in a different
paragraph).
When using the version of org-mode that shipped with emacs 29.1 (Org mode
version 9.6.6 (release_9.6.6 @ /usr/share/emacs/29.1/lisp/org/)) the "@@latex:"
gets parsed as plaintext.
The docs seem to show that a "@@" is required as the end of an export snippet
based on the pattern "@@BACKEND:VALUE@@":
https://orgmode.org/worg/org-syntax.html#Export_Snippets
AST from org-mode in main:
```
(org-data
(:standard-properties
[1 71 1 71 0 1 nil nil nil 3 71 org-data nil nil nil nil nil #<buffer
*scratch*>]
:path nil :CATEGORY nil)
(section
(:standard-properties
[1 71 1 71 0 1 nil nil nil 1 71 first-section nil nil #0 nil nil #<buffer
*scratch*>])
(paragraph
(:standard-properties
[1 13 1 10 3 1 nil nil nil nil nil top-comment nil nil #1 nil nil #<buffer
*scratch*>])
(export-snippet
(:standard-properties
[1 9 nil nil 0 nil nil nil nil nil nil nil nil nil #2 nil nil #<buffer
*scratch*>]
:back-end "latex" :value nil))
#("\n" 0 1
(:parent #2)))
(paragraph
(:standard-properties
[13 68 13 65 3 13 nil nil nil nil nil nil nil nil #1 nil nil #<buffer
*scratch*>])
(latex-fragment
(:standard-properties
[13 46 nil nil 1 nil nil nil nil nil nil nil nil nil #2 nil nil #<buffer
*scratch*>]
:value "\\documentclass[margin,11pt]{res}"))
#("% default is 10 pt\n" 0 19
(:parent #2)))
(paragraph
(:standard-properties
[68 71 68 71 0 68 nil nil nil nil nil nil nil nil #1 nil nil #<buffer
*scratch*>])
#("@@\n" 0 3
(:parent #2)))))
```
AST from org-mode in emacs 29.1:
```
(org-data
(:begin 1 :contents-begin 1 :contents-end 71 :end 71 :robust-begin 3
:robust-end 69 :post-blank 0 :post-affiliated 1 :path nil :mode org-data
:CATEGORY nil :granularity nil)
(section
(:begin 1 :end 71 :contents-begin 1 :contents-end 71 :robust-begin 1
:robust-end 69 :post-blank 0 :post-affiliated 1 :mode first-section
:granularity nil :parent #0)
(paragraph
(:begin 1 :end 13 :contents-begin 1 :contents-end 10 :post-blank 3
:post-affiliated 1 :mode top-comment :granularity nil :parent #1)
#("@@latex:\n" 0 9
(:parent #2)))
(paragraph
(:begin 13 :end 68 :contents-begin 13 :contents-end 65 :post-blank 3
:post-affiliated 13 :mode nil :granularity nil :parent #1)
(latex-fragment
(:value "\\documentclass[margin,11pt]{res}" :begin 13 :end 46 :post-blank 1
:parent #2))
#("% default is 10 pt\n" 0 19
(:parent #2)))
(paragraph
(:begin 68 :end 71 :contents-begin 68 :contents-end 71 :post-blank 0
:post-affiliated 68 :mode nil :granularity nil :parent #1)
#("@@\n" 0 3
(:parent #2)))))
```
--
Tom Alexander
