How do I prevent Vim from indenting lines containing <screen/> XML tags?

Question

I edit a lot of Docbook files. <screen/> blocks are normally unindented in Docbook source code. How do I tell Vim to shift the <screen> tag to the very left when entering such tag? After closing that block with </screen>, it would be nice to continue indenting as it was before the starting <screen>. I use:

filetype plugin indent on
set smartindent

Answer 1

The filetype indentation rules (filetype plugin indent on) should take precedence over whatever set smartindent defines.

Is your filetype getting recognized? What does set filetype? return?

I see in $VIMRUNTIME/filetype.vim that .sgm and .sgml files are either recognized as sgml, sgmllnx, or docbk filetypes. It depends on the text on the first line.

" SGML
au BufNewFile,BufRead *.sgm,*.sgml
    \ if getline(1).getline(2).getline(3).getline(4).getline(5) =~? 'linuxdoc' |
    \   setf sgmllnx |
    \ elseif getline(1) =~ '<!DOCTYPE.*DocBook' || getline(2) =~ '<!DOCTYPE.*DocBook' |
    \   let b:docbk_type = "sgml" |
    \   let b:docbk_ver = 4 |
    \   setf docbk |
    \ else |
    \   setf sgml |
    \ endif

There is a $VIMRUNTIME/indent/docbk.vim file (which follows xml rules) but there's not a $VIMRUNTIME/indent/sgml.vim or $VIMRUNTIME/indent/sgmllnx.vim file.

If the filetype is getting set by Vim to sgml or sgmllnx, then the smartindent indentation rules will apply. If the filetype is getting set by Vim to docbk, then the rules in $VIMRUNTIME/indent/docbk.vim should apply. The docbk.vim indentation rules follow xml rules, so it's very smart about indenting by tags.