If you try to generate html version of your plain TeX document using a combination of pdfTeX and TeX4ht, you will find terrible mismatches and html version will not be generated. The reason for the problem is TeX4ht needs a dvi output from which it extracts the html while pdfTeX generates a pdf by default. Therefore, TeX4ht post-processor will cry that there is no jobname.dvi. However,
ht 'pdftex -output-format=dvi' bk7.tex
will work. But the html file will have only the ASCII characters of your document and will not be valid html. To make a valid html from a plain TeX file, you have to do the following trick.
You need to wrap up your TeX source file with following code:
\input amstex
\documentstyle{amsppt}
\csname tex4ht\endcsname
\document
. . . source of your plain TeX document . . .
\enddocument
The following command might be handy to generate file.html assuming your input file name is file.tex:
httex file "xhtml,html4.4ht,unicode.4ht,mathml.4ht"
Plain TeX users might miss this trick when they happen to use TeX4ht which is supposed to work out of box in the case of LaTeX documents.
