A line space between paragraphs, as @Fuellemann suggests, creates new paragraph <p> tag. It won’t create a line break. Paragraphs are styled to have margin on the bottom, which makes it appear you’ve added a <br> because of the empty line.
Two empty lines does not create a <br> or an extra <br>. In fact it does not even create an empty <p> tag pair. Why? Because the editor is smart enough to know not to insert a random, errant, empty <p> tag pair.
The Custom Summary is different from the main body. The main body of the blog post can handle different HTML markup and what not as it is in the body of the Markdown file. The Custom Summary will handle only Markdown for the most part. This is because it is a custom field within the YAML of the blog post’s Markdown file. This is by design so that we can reload the Custom Summary in the Editor as something separate from the main blog post’s body content.
TL;DR – don’t use HTML markup, video embeds, etc in the Custom Summary field.
I have heard of YAML, but I’m not familiar with it. I’ve just done a bit of reading up on it, but I’m still not sure if I should be able to put a line break in the custom summary box (and so the issue described above is a bug), or if it’s designed in such a way that only a block of text (no line breaks) is possible. Hopefully @elixirgraphics can clear that up for me?
Sorry I don’t think I’m clear on what you’re asking. Or maybe I just didn’t explain myself clearly enough before. Sorry if that is the case.
Putting HTML markup in the Custom Summary field should not be done. Your results you are seeing are neither expected or not expected. The Custom Summary isn’t designed to have HTML markup placed within it.
HTML Markup in the Custom Summary field would also include a space between paragraphs as that creates HTML markup. The Custom Summary field was not intended to have more than a Summary block of text. I can look at encoding it to allow this in the future. I don’t know if it will be possible or not.
As for some of the other questions, suggestions, etc posted yesterday:
This will not work within the field, as it all gets wrapped in quotation marks when it is written to the file.
</br> is not valid HTML markup.
Like I said though, the Custom Summary field is only designed for a block of text, using Markdown. Adding HTML markup to it, in whatever fashion, will have undesired results. I will look at this in a future update to see what is possible, but as of now this is how it is made to work.
Before I started to add in all the code options, I inserted a line break by simply hitting carriage return on the keyboard. But it didn’t work; the text after the return got removed. So my question was, is this expected, as in, are we not able to put he text in the summary over more than one line?
And I think this answers the question: Blocks of text all on the same line, no line breaks, no matter how they are inserted?
The way the layouts are generated is more complex than they may seem on the surface as they have to take a lot of the user selected features and possibilities into consideration. Adding one is quite a bit of work. I’ll note this as a feature request, but this definitely will not be in the next update though.