HTML Export generates files in UTF-8 format using Unix-style line endings (line feed character, '\n'). The data excludes a BOM (Byte Order Marker). Although using a BOM is supposedly the correct standards-based approach few apps have adopted it correctly resulting in some processes mishandling the file.
HTML export can export all manner of mark-up (HTML, MMD, XML, JSON, etc.) but for actual HTML it is advisable to add the following for thesection of the exported page's source:
<meta http-equiv="content-type" content="text/html; charset=utf-8">
That meta element makes it even easier for ensure a web browser to understand unambiguously the encoding to expect within web page it is opening.