Thanks for your response, however it has not resolved the issue for me, but has prompted me to explore the various options more fully. Here is what I have found:
I am able to use some Wiki tags with this option - including '''' ...''' for bold, '' ... '' for italic. # for numbered lists, and * for bulleted lists.
I can use single brackets for [Wiki links], however when I try an
expression of the form [http://www.eytv4scf.net Education, Youth,
Technology and Values for a Sustainable Common Future], I don't get the desired result.
The Wiki tags - = ... =, == ... ==, etc. do not translate into header levels 1, 2 ...; and I get some weird formatting with the use of : for indentation; a single colon has no effect, multiple colons - :: or ::: - produce a series of indentations
Although the option is labeled No HTML, I find that I can use some HTML tags - including <b> ... </b>, <i> ... </i>, <h1> ... </h1>, <h2> ... </h2>, <div style=" ...."> ... </div> and <table> tags.
However, other HTML tags such as <a href=" ... "> ... </a>, and <img src=" ...."> do not work; the former is converted to simple anchor tags in the source - <a> ... </a> - and the latter shows neither image nor tags.
In this mode, the Wiki tags behave - or misbehave - the same way as described above, however, somewhat inexplicably, this option allows more limited use of HTML tags than does the No HTML. with bold, italic and header tags working correctly. but <div> and <table> tags bo not work, and appear as written.
This option allows me full use of HTML tags, but does not translate any of the Wiki tags.
Btw I don't especially like Moodle's HTML editor - although I will not go into details of my critique here - and like MSWord even less, having had the good fortune to use WordPerfect for 25 years.
I generally use the Text mode for adding HTML formatting and links in Moodle, and my preference is for Wiki coding - supplemented by HTML when appropriate - that I find simpler and cleaner. I particulalry appreciate the Wiki header tags and the automatic table of contents that is generated from the Wiki header tags in all other Wiki spaces I have worked in.