Update runtime files.
diff --git a/runtime/syntax/rmd.vim b/runtime/syntax/rmd.vim
index 0543535..a263890 100644
--- a/runtime/syntax/rmd.vim
+++ b/runtime/syntax/rmd.vim
@@ -1,123 +1,118 @@
 " markdown Text with R statements
 " Language: markdown with R code chunks
 " Homepage: https://github.com/jalvesaq/R-Vim-runtime
-" Last Change: Sat Jan 28, 2017  10:06PM
-"
-" CONFIGURATION:
-"   To highlight chunk headers as R code, put in your vimrc (e.g. .config/nvim/init.vim):
-"   let rmd_syn_hl_chunk = 1
+" Last Change: Sat Aug 25, 2018  03:44PM
 "
 "   For highlighting pandoc extensions to markdown like citations and TeX and
 "   many other advanced features like folding of markdown sections, it is
 "   recommended to install the vim-pandoc filetype plugin as well as the
 "   vim-pandoc-syntax filetype plugin from https://github.com/vim-pandoc.
-"
-" TODO:
-"   - Provide highlighting for rmarkdown parameters in yaml header
+
 
 if exists("b:current_syntax")
   finish
 endif
 
-" load all of pandoc info, e.g. from
+" Configuration if not using pandoc syntax:
+" Add syntax highlighting of YAML header
+let g:rmd_syn_hl_yaml = get(g:, 'rmd_syn_hl_yaml', 1)
+" Add syntax highlighting of citation keys
+let g:rmd_syn_hl_citations = get(g:, 'rmd_syn_hl_citations', 1)
+" Highlight the header of the chunk of R code
+let g:rmd_syn_hl_chunk = get(g:, 'g:rmd_syn_hl_chunk', 0)
+
+" Pandoc-syntax has more features, but it is slower.
 " https://github.com/vim-pandoc/vim-pandoc-syntax
+let g:pandoc#syntax#codeblocks#embeds#langs = get(g:, 'pandoc#syntax#codeblocks#embeds#langs', ['r'])
 runtime syntax/pandoc.vim
 if exists("b:current_syntax")
-  let rmdIsPandoc = 1
-  unlet b:current_syntax
-else
-  let rmdIsPandoc = 0
-  runtime syntax/markdown.vim
-  if exists("b:current_syntax")
-    unlet b:current_syntax
-  endif
-
-  " load all of the yaml syntax highlighting rules into @yaml
-  syntax include @yaml syntax/yaml.vim
-  if exists("b:current_syntax")
-    unlet b:current_syntax
-  endif
-
-  " highlight yaml block commonly used for front matter
-  syntax region rmdYamlBlock matchgroup=rmdYamlBlockDelim start="^---" matchgroup=rmdYamlBlockDelim end="^---" contains=@yaml keepend fold
+  " Fix recognition of R code
+  syn region pandocDelimitedCodeBlock_r start=/^```{r\>.*}$/ end=/^```$/ contained containedin=pandocDelimitedCodeBlock contains=@R
+  syn region rmdrInline matchgroup=rmdInlineDelim start="`r "  end="`" contains=@R containedin=pandocLaTeXRegion,yamlFlowString keepend
+  hi def link rmdInlineDelim Delimiter
+  let b:current_syntax = "rmd"
+  finish
 endif
 
-if !exists("g:rmd_syn_langs")
-  let g:rmd_syn_langs = ["r"]
-else
-  let s:hasr = 0
-  for s:lng in g:rmd_syn_langs
-    if s:lng == "r"
-      let s:hasr = 1
-    endif
-  endfor
-  if s:hasr == 0
-    let g:rmd_syn_langs += ["r"]
+let s:cpo_save = &cpo
+set cpo&vim
+
+" R chunks will not be highlighted by syntax/markdown because their headers
+" follow a non standard pattern: "```{lang" instead of "^```lang".
+" Make a copy of g:markdown_fenced_languages to highlight the chunks later:
+if exists('g:markdown_fenced_languages')
+  if !exists('g:rmd_fenced_languages')
+    let g:rmd_fenced_languages = deepcopy(g:markdown_fenced_languages)
+    let g:markdown_fenced_languages = []
   endif
+else
+  let g:rmd_fenced_languages = ['r']
 endif
 
-for s:lng in g:rmd_syn_langs
-  exe 'syntax include @' . toupper(s:lng) . ' syntax/'. s:lng . '.vim'
-  if exists("b:current_syntax")
-    unlet b:current_syntax
-  endif
-  exe 'syntax region rmd' . toupper(s:lng) . 'Chunk start="^[ \t]*``` *{\(' . s:lng . '\|r.*engine\s*=\s*["' . "']" . s:lng . "['" . '"]\).*}$" end="^[ \t]*```$" contains=@' . toupper(s:lng) . ',rmd' . toupper(s:lng) . 'ChunkDelim keepend fold'
+runtime syntax/markdown.vim
 
-  if exists("g:rmd_syn_hl_chunk") && s:lng == "r"
-    " highlight R code inside chunk header
-    syntax match rmdRChunkDelim "^[ \t]*```{r" contained
-    syntax match rmdRChunkDelim "}$" contained
+" Now highlight chunks:
+for s:type in g:rmd_fenced_languages
+  if s:type =~ '='
+    let s:lng = substitute(s:type, '=.*', '')
+    let s:nm  = substitute(s:type, '.*=', '')
   else
-    exe 'syntax match rmd' . toupper(s:lng) . 'ChunkDelim "^[ \t]*```{\(' . s:lng . '\|r.*engine\s*=\s*["' . "']" . s:lng . "['" . '"]\).*}$" contained'
+    let s:lng = s:type
+    let s:nm  = s:type
   endif
-  exe 'syntax match rmd' . toupper(s:lng) . 'ChunkDelim "^[ \t]*```$" contained'
+  unlet! b:current_syntax
+  exe 'syn include @Rmd'.s:nm.' syntax/'.s:lng.'.vim'
+  if g:rmd_syn_hl_chunk
+    exe 'syn region rmd'.s:nm.'ChunkDelim matchgroup=rmdCodeDelim start="^\s*```\s*{\s*'.s:nm.'\>" matchgroup=rmdCodeDelim end="}$" keepend containedin=rmd'.s:nm.'Chunk contains=@Rmd'.s:nm
+    exe 'syn region rmd'.s:nm.'Chunk start="^\s*```\s*{\s*'.s:nm.'\>.*$" matchgroup=rmdCodeDelim end="^\s*```\ze\s*$" keepend contains=rmd'.s:nm.'ChunkDelim,@Rmd'.s:nm
+  else
+    exe 'syn region rmd'.s:nm.'Chunk matchgroup=rmdCodeDelim start="^\s*```\s*{\s*'.s:nm.'\>.*$" matchgroup=rmdCodeDelim end="^\s*```\ze\s*$" keepend contains=@Rmd'.s:nm
+  endif
+  exe 'syn region rmd'.s:nm.'Inline matchgroup=rmdInlineDelim start="`'.s:nm.' "  end="`" contains=@Rmd'.s:nm.' keepend'
 endfor
+unlet! s:type
 
+hi def link rmdInlineDelim Delimiter
+hi def link rmdCodeDelim Delimiter
 
-" also match and syntax highlight in-line R code
-syntax region rmdrInline matchgroup=rmdInlineDelim start="`r "  end="`" contains=@R containedin=pandocLaTeXRegion,yamlFlowString keepend
-" I was not able to highlight rmdrInline inside a pandocLaTeXCommand, although
-" highlighting works within pandocLaTeXRegion and yamlFlowString. 
-syntax cluster texMathZoneGroup add=rmdrInline
-
-" match slidify special marker
-syntax match rmdSlidifySpecial "\*\*\*"
-
-
-if rmdIsPandoc == 0
-  syn match rmdBlockQuote /^\s*>.*\n\(.*\n\@<!\n\)*/ skipnl
-  " LaTeX
-  syntax include @LaTeX syntax/tex.vim
-  if exists("b:current_syntax")
-    unlet b:current_syntax
-  endif
-  " Inline
-  syntax match rmdLaTeXInlDelim "\$"
-  syntax match rmdLaTeXInlDelim "\\\$"
-  syn region texMathZoneX	matchgroup=Delimiter start="\$" skip="\\\\\|\\\$"	matchgroup=Delimiter end="\$" end="%stopzone\>"	contains=@texMathZoneGroup
-  " Region
-  syntax match rmdLaTeXRegDelim "\$\$" contained
-  syntax match rmdLaTeXRegDelim "\$\$latex$" contained
-  syntax match rmdLaTeXSt "\\[a-zA-Z]\+"
-  syntax region rmdLaTeXRegion start="^\$\$" skip="\\\$" end="\$\$$" contains=@LaTeX,rmdLaTeXRegDelim keepend
-  syntax region rmdLaTeXRegion2 start="^\\\[" end="\\\]" contains=@LaTeX,rmdLaTeXRegDelim keepend
-  hi def link rmdBlockQuote Comment
-  hi def link rmdLaTeXSt Statement
-  hi def link rmdLaTeXInlDelim Special
-  hi def link rmdLaTeXRegDelim Special
+" You don't need this if either your markdown/syntax.vim already highlights
+" the YAML header or you are writing standard markdown
+if g:rmd_syn_hl_yaml
+  " Minimum highlighting of yaml header
+  syn match rmdYamlFieldTtl /^\s*\zs\w*\ze:/ contained
+  syn match rmdYamlFieldTtl /^\s*-\s*\zs\w*\ze:/ contained
+  syn region yamlFlowString matchgroup=yamlFlowStringDelimiter start='"' skip='\\"' end='"' contains=yamlEscape,rmdrInline contained
+  syn region yamlFlowString matchgroup=yamlFlowStringDelimiter start="'" skip="''"  end="'" contains=yamlSingleEscape,rmdrInline contained
+  syn match  yamlEscape contained '\\\%([\\"abefnrtv\^0_ NLP\n]\|x\x\x\|u\x\{4}\|U\x\{8}\)'
+  syn match  yamlSingleEscape contained "''"
+  syn region pandocYAMLHeader matchgroup=rmdYamlBlockDelim start=/\%(\%^\|\_^\s*\n\)\@<=\_^-\{3}\ze\n.\+/ end=/^\([-.]\)\1\{2}$/ keepend contains=rmdYamlFieldTtl,yamlFlowString
+  hi def link rmdYamlBlockDelim Delimiter
+  hi def link rmdYamlFieldTtl Identifier
+  hi def link yamlFlowString String
 endif
 
-for s:lng in g:rmd_syn_langs
-  exe 'syn sync match rmd' . toupper(s:lng) . 'SyncChunk grouphere rmd' . toupper(s:lng) . 'Chunk /^[ \t]*``` *{\(' . s:lng . '\|r.*engine\s*=\s*["' . "']" . s:lng . "['" . '"]\)/'
-endfor
-
-hi def link rmdYamlBlockDelim Delim
-for s:lng in g:rmd_syn_langs
-  exe 'hi def link rmd' . toupper(s:lng) . 'ChunkDelim Special'
-endfor
-hi def link rmdInlineDelim Special
-hi def link rmdSlidifySpecial Special
+" You don't need this if either your markdown/syntax.vim already highlights
+" citations or you are writing standard markdown
+if g:rmd_syn_hl_citations
+  " From vim-pandoc-syntax
+  " parenthetical citations
+  syn match pandocPCite /\^\@<!\[[^\[\]]\{-}-\{0,1}@[[:alnum:]_][[:alnum:]à-öø-ÿÀ-ÖØ-ß_:.#$%&\-+?<>~\/]*.\{-}\]/ contains=pandocEmphasis,pandocStrong,pandocLatex,pandocCiteKey,@Spell,pandocAmpersandEscape display
+  " in-text citations with location
+  syn match pandocICite /@[[:alnum:]_][[:alnum:]à-öø-ÿÀ-ÖØ-ß_:.#$%&\-+?<>~\/]*\s\[.\{-1,}\]/ contains=pandocCiteKey,@Spell display
+  " cite keys
+  syn match pandocCiteKey /\(-\=@[[:alnum:]_][[:alnum:]à-öø-ÿÀ-ÖØ-ß_:.#$%&\-+?<>~\/]*\)/ containedin=pandocPCite,pandocICite contains=@NoSpell display
+  syn match pandocCiteAnchor /[-@]/ contained containedin=pandocCiteKey display
+  syn match pandocCiteLocator /[\[\]]/ contained containedin=pandocPCite,pandocICite
+  hi def link pandocPCite Operator
+  hi def link pandocICite Operator
+  hi def link pandocCiteKey Label
+  hi def link pandocCiteAnchor Operator
+  hi def link pandocCiteLocator Operator
+endif
 
 let b:current_syntax = "rmd"
 
+let &cpo = s:cpo_save
+unlet s:cpo_save
+
 " vim: ts=8 sw=2