I skimmed the abstracts of TUG 2014 and stumbled over *"Fake spaces" with pdfTeX — the best of both worlds* by Ross Moore. The abstract says:

With the 2014 version of TeX Live, new primitives are included within

pdfTeX that allow a`pdffakespace`

to be inserted into the PDF

content stream, occurring between words and at the end of lines.

In particular, this is intriguing:

Also to be shown is how a fake space allows extra

material, such as the LaTeX source of inline or displayed mathematics,

to be included invisibly within the PDF. With a Select/Copy/Paste of

the mathematical expression, this included source coding comes along

with the pasted text.

Unfortunately, there are no slides available, and the proceedings do not seem to contain anything about this (not that I could access them, as a non-member).

What are current applications of these fake spaces? In particular, has copy-paste of mathematics been implemented so that it may be used without disadvantages?

## Best Answer

In reference to your point,

In particular, has copy-paste of mathematics been implemented so that it may be used without disadvantagesI don't know the particulars of what you cite, but the

`accsupp`

package allows different things to be displayed in a PDF versus what shows up in a copy paste.REVISED SOLUTION (using Raphael's suggestion of

`\detokenize`

)It would seem that

`\detokenize`

alleviates the need for separate arguments for the typeset and actual-pdf text, which will greatly streamline the use of this approach. I extend my thanks to him.I also show how this even works for

`\displaystyle`

math.Here is the PDF's appearance:

Now, when I go into Adobe Reader on the produced PDF file and hit ctl-A ctl-C to copy the whole document, the paste into a text file will appear as:

ORIGINAL EDITED SOLUTION to allow optional argument with different "ActualText" content, for example, to use

`\noexpand`

for certain math arguments.