diff --git a/autoload/tcomment.vim b/autoload/tcomment.vim
index 64b5866..aead64c 100644
--- a/autoload/tcomment.vim
+++ b/autoload/tcomment.vim
@@ -2,8 +2,8 @@
 " @Website:     http://www.vim.org/account/profile.php?user_id=4037
 " @License:     GPL (see http://www.gnu.org/licenses/gpl.txt)
 " @Created:     2007-09-17.
-" @Last Change: 2019-03-17.
-" @Revision:    2036
+" @Last Change: 2020-03-14.
+" @Revision:    2039
 
 scriptencoding utf-8
 
@@ -279,6 +279,16 @@ endf
 "         postprocess_uncomment .. Run a |printf()| expression with 2 
 "                              placeholders on uncommented lines, e.g. 
 "                              'norm! %sgg=%sgg'.
+"         choose           ... A list of commend definitions (a 
+"                              dictionary as defined above) that may 
+"                              contain an `if` key referring to an 
+"                              expression; if this condition evaluates 
+"                              to true, the item will be selected; the 
+"                              last item in the list will be selected 
+"                              anyway (see the bib definition for an 
+"                              example)
+"         if               ... an |eval()|able expression (only valid 
+"                              within a choose list, see above)
 "   2. 1-2 values for: ?commentPrefix, ?commentPostfix
 "   3. a dictionary (internal use only)
 "
diff --git a/autoload/tcomment/type.vim b/autoload/tcomment/type.vim
index 0c45f98..e9f7a8b 100644
--- a/autoload/tcomment/type.vim
+++ b/autoload/tcomment/type.vim
@@ -2,8 +2,8 @@
 " @Website:     http://www.vim.org/account/profile.php?user_id=4037
 " @License:     GPL (see http://www.gnu.org/licenses/gpl.txt)
 " @Created:     2007-09-17.
-" @Last Change: 2018-09-03.
-" @Revision:    33
+" @Last Change: 2020-03-12.
+" @Revision:    42
 
 if exists(':Tlibtrace') != 2
     command! -nargs=+ -bang Tlibtrace :
@@ -90,11 +90,36 @@ endf
 " Return b:tcomment_def_{NAME} if the variable exists. Otherwise return 
 " the comment definition as set with |tcomment#type#Define|.
 function! tcomment#type#GetDefinition(name, ...) abort
+    Tlibtrace 'tcomment', a:name
     if exists('b:tcomment_def_'. a:name)
-        return b:tcomment_def_{a:name}
+        let def = b:tcomment_def_{a:name}
     else
-        return get(s:definitions, a:name, a:0 >= 1 ? a:1 : '')
+        let def = get(s:definitions, a:name, a:0 >= 1 ? a:1 : '')
     endif
+    Tlibtrace 'tcomment', def
+    if has_key(def, 'choose')
+        let def = copy(def)
+        let defs = def.choose
+        let ndefs = len(defs)
+        Tlibtrace 'tcomment', ndefs
+        for idef in range(ndefs)
+            let cdef = defs[idef]
+            Tlibtrace 'tcomment', idef, cdef
+            if idef == ndefs - 1
+                let choose = 1
+            else
+                let choose = eval(cdef.if)
+            endif
+            Tlibtrace 'tcomment', choose
+            if choose
+                call remove(def, 'choose')
+                let def = extend(def, cdef)
+                break
+            endif
+        endfor
+    endif
+    Tlibtrace 'tcomment', def
+    return def
 endf
 
 
diff --git a/autoload/tcomment/types/default.vim b/autoload/tcomment/types/default.vim
index e42ba4d..6cc1705 100644
--- a/autoload/tcomment/types/default.vim
+++ b/autoload/tcomment/types/default.vim
@@ -1,8 +1,8 @@
 " @Author:      Tom Link (mailto:micathom AT gmail com?subject=[vim])
 " @Website:     https://github.com/tomtom
 " @License:     GPL (see http://www.gnu.org/licenses/gpl.txt)
-" @Last Change: 2019-03-17
-" @Revision:    18
+" @Last Change: 2020-03-12
+" @Revision:    23
 
 call tcomment#type#Define('aap',              '# %s'             )
 call tcomment#type#Define('ada',              '-- %s'            )
@@ -14,7 +14,7 @@ call tcomment#type#Define('applescript_inline','# %s'            )
 call tcomment#type#Define('asciidoc',         '// %s'            )
 call tcomment#type#Define('asm',              '; %s'             )
 call tcomment#type#Define('asterisk',         '; %s'             )
-call tcomment#type#Define('bib',              '%% %s'            )
+call tcomment#type#Define('bib',              {'choose': [{'if': 'col(".") <= 1', 'commentstring': '@Comment{%s}'}, {'commentstring': '%% %s'}]})
 call tcomment#type#Define('blade',            '{{-- %s --}}'     )
 call tcomment#type#Define('blade_block',      '{{--%s--}}'       )
 call tcomment#type#Define('blade_inline',     '{{-- %s --}}'     )
diff --git a/doc/tcomment.txt b/doc/tcomment.txt
index a7cc627..9d1f43c 100644
--- a/doc/tcomment.txt
+++ b/doc/tcomment.txt
@@ -479,6 +479,16 @@ tcomment#Comment(beg, end, ...)
             postprocess_uncomment .. Run a |printf()| expression with 2 
                                  placeholders on uncommented lines, e.g. 
                                  'norm! %sgg=%sgg'.
+            choose           ... A list of commend definitions (a 
+                                 dictionary as defined above) that may 
+                                 contain an `if` key referring to an 
+                                 expression; if this condition evaluates 
+                                 to true, the item will be selected; the 
+                                 last item in the list will be selected 
+                                 anyway (see the bib definition for an 
+                                 example)
+            if               ... an |eval()|able expression (only valid 
+                                 within a choose list, see above)
       2. 1-2 values for: ?commentPrefix, ?commentPostfix
       3. a dictionary (internal use only)