Fix similar to syntax and wording of current_transaction, current_con…

…nection

Copied from ddf22cc

src/docs/asciidoc/en/refdocs/fblangref40/_fblangref40-commons.adoc

@@ -1084,7 +1084,7 @@ Feel free to skip it and read the next section, <<fblangref40-commons-buildregex
 <escaped character> ::=
   <escape-char> <special character> | <escape-char> <escape-char>
 
-<special character> ::= _any of the characters **[]()|^-+*%_?{**_
+<special character> ::= __any of the characters **[]()|^-+*%\_?{}**__
 
 <non-escaped character> ::=
   _any character that is not a <special character>_

src/docs/asciidoc/en/refdocs/fblangref40/_fblangref40-context-vars.adoc

@@ -18,10 +18,8 @@ CURRENT_CONNECTION
 
 `CURRENT_CONNECTION` contains the unique identifier of the current connection.
 
-The value of `CURRENT_CONNECTION` is stored on the database header page and reset to 0 upon restore.
-Since version 2.1, it is incremented upon every new connection.
-(In previous versions, it was only incremented if the client read it during a session.)
-As a result, `CURRENT_CONNECTION` now indicates the number of connections since the creation -- or most recent restoration -- of the database.
+Its value is derived from a counter on the database header page, which is incremented for each new connection.
+When a database is restored, this counter is reset to zero.
 
 .Examples
 [source]
@@ -252,8 +250,8 @@ CURRENT_TRANSACTION
 
 `CURRENT_TRANSACTION` contains the unique identifier of the current transaction.
 
-The value of `CURRENT_TRANSACTION` is stored on the database header page and reset to 0 upon restore.
-It is incremented with every new transaction.
+Its value is derived from a counter on the database header page, which is incremented for each new transaction.
+When a database is restored, this counter is reset to zero.
 
 .Examples
 [source]