This is really weird.

restart;

eq:=phi(f(x,y(x),diff(y(x),x)),g(x,y(x),diff(y(x),x)));

Does any one see a "||" in the above? I do not. Then why Maple shows this:

r := cat("dsolve(",eq,",y(x))");

r:="dsolve("||phi(f(x,y(x),y'(x)),g(x,y(x),y'(x)))||",y(x))"

This is Maple 2015 on windows. Running in worksheet mode

Here is screen shot

This problem does not show up all the time. For example, this works ok:

No "||" added. The problem with all the above, is that I can't make it all as a string in the first example above. I am trying to make a string of "dsolve(" + ode + "),y(x)"

Here is the display options

thank you