Thanks for trying to help me Brynn. I'm not very good at explaining. I'll try to do a step by step of what I did.
Made a file in Inkscape 0.92 containing some text + other stuff. The font I used is available for both Inkscape and Gimp (I can type in Gimp a text string with the font; I can use the same font in Inkscape to type a text string)
Saved the file in Inkscape 0.92
Opened the file in Gimp 2.8.18 and the text was now a different font.
This made me think it was a problem with Gimp so un-installed/re-installed with a fresh download and after having tried the file again and it did not work thought it would be a problem with my version of Inkscape 0.92 so un-installed/re-installed that too with fresh downloads but when that didn't give a different result I did some testing.
First made another file on the same computer with 2 different fonts available to both Inkscape and Gimp and all my other programs on that computer (#1). This file had two text strings one with each of the two fonts. Tested both fonts in Gimp using the text tool in there to make sure it could display the fonts correctly. Again this file made Inkscape 0.92 could not be opened correctly in Gimp 2.8.18
I made a file in Inkscape 0.91 on another computer(#2) using the same two fonts which is also available on that computer (not yet updated Inkscape to 0.92 on that one), saved and tried opening that file in Gimp 2.8.18 first on the same computer (#2) that created the file and then on the original computer (#1) and encountered no problems on either computers (#1 or #2).
I then dug back into my files and found a file created on computer (#1) in Inkscape 0.48.5 with text in one of the fonts tested above. Opened beautifully in Gimp with no change of font.
At this stage I used Beyond Compare (the data compare utility program); compared the two test files above and found the differences in the files created in Inkscape 0.91 and 0.92. This turned out to be the pings I mentioned in my original post - they are added in files created in Inkscape 0.92 but absent in Inkscape 0.91.
Using Wordpad I removed the pings in the file I had made in Inkscape 0.92 and saved it from Wordpad. This new file I can open in Gimp 2.8.18 and the fonts display correctly. It can of course still be opened in Inkscape 0.92 as well as in 0.91.
You ask if this happens with all the fonts - honestly I don't know; I have quite a few on my system (far too many according to DH) but testing 3 different ones and the same thing happens makes me draw the conclusion that it probably happens to them all.
As to where the problems lies - personally I think it is in Inkscape 0.92 seeing that it has worked perfectly all right for a long time whether I used 0.48.5 or 0.91 and yesterday was the first day doing anything with text in 0.92 that I needed to do something to in Gimp.
Seeing I have tested the files on two 'puters it is not likely I think to have anything to do with computer and as I can pinpoint the exact difference (the pings around the font name) when I open the .svg file in Wordpad there must be a setting in Inkscape 0.92 that creates these that was not present in previous versions of Inkscape.
I will try attaching files to this message and see if it works
The first and second files are not edited in Wordpad bus as they were saved in Inkscape whereas the last one Test font 0.92 no pings.svg is the one edited in Wordpad where I removed the pings.
Hope this second post makes more sense than the first
Maga