I am looking at the help pages, and I see Maple code using symbols never seen in Maple language before.

I tried to do ?&under to get help on this new Maple language command/symbol, but help does not show it. I read help Neutral Operators but do not understand it.

What does the following mean in plain Maple code?

And what does the following mean using Plain Maple code:

Could the above be written without using these `&` things?  I am having hard time understanding what the code is doing because of these. Never used them before.

These are from help on "Definition of a Structured Type in Maple"

On the maple cloud, I see that current version is 38 for Physics 

After I installed, I typed

Physics:-Version();

It gives 
  "......\maple\toolbox\2018\Physics Updates\lib\Physics Updates.maple", 2018, May 8, 17:49 hours

I was expecting to see "38".  Why does Physics:-Version(); does not give the version number as shown on Maple cloud? Using only a date for a version number is not a good idea. There should be a number there. (date can also be included, but a number should be the official version number).

Is there another command to use to obtain Version number "38"?

Does each package shown on cloud support packageName:-Version()? I tried this command on another package I have, but I got an error saying it does not Version() 

OrthogonalExpansions:-Version();
Error, Version is not a command in the OrthogonalExpansions package
 

Yet, on cloud, it says the version number is "1" for the above package. What does the version number shown on the cloud then really mean?

I do not know what I am doing wrong. I am trying to plot each of the solutions to an ODE. One of the solutions Maple gives is  LegendreQ((1/2)*sqrt(5)-1/2, x) and the other is LegendreP((1/2)*sqrt(5)-1/2, x)

Maple can plot the  LegendreP, but gives an error plotting LegendreQ((1/2)*sqrt(5)-1/2, x)

ode:=(1-x^2)*diff(y(x),x$2)-2*x*diff(y(x),x)+y(x)=0:
sol:=dsolve(ode,y(x));

sol := y(x) = _C1*LegendreP((1/2)*sqrt(5)-1/2, x)+_C2*LegendreQ((1/2)*sqrt(5)-1/2, x)

Now when I do 

plot(LegendreQ((1/2)*sqrt(5)-1/2, x),x=-1..1);

Maple says

Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct
 

Why is that? I tried x=-0.5..1 and x=0.5..1 and keep getting same error message. It works ok for 

plot(LegendreP((1/2)*sqrt(5)-1/2, x),x=-1..1);

Mathematica can plot both with no problem.

These are some basic questions on using packages from Maple Cloud. I only used it once or twice so far.

When I click on the "cloud" icon, on top right corner of the menu, I see on the left panel "Math apps" then below it "packages" and then below it is says "installed".

When I click on "installed", I see one package that I installed sometime ago.

1) How does one uninstall a package listed in the "installed" list? I see no option to do this.

2) How does one know if the "installed" package needs to be updated or not? And if so, how does one updated it? 

3) In the "packages" list, I see "physics Updates".  Now,  I did install this earlier (1-2 weeks ago). Then why is it not listed also under the "installed" list? And how does one know if they have installed a package that shows in the "packages" list?

There is no marker or anything there to tell one they have installed it or not.  Is one supposed to go look in the "installed" list to manually check if they installed it or not?

4)What happens if one install a package/app they have installed before. Will the new package overwrite the older version automatically?

5) It seems packages installed go to some temporary folder. Is there a way to configure it, so that all packages installed go to some other user defined folder. This way, if one moves to a new PC or such, they do not lose all the packages they have installed? 

It seems these basic functionalities are missing: 1. option to uninstall a package. 2. Marker of some kind to tell one if they installed something listed in the "packages" list. 3. Marker to tell one if a package they have installed needs to be updated if there is a newer version on the cloud.

Only options I see are: Install, view, share link and search. That is all. All the above also applies to "Math apps".

Using Maple 2018 on windows.

Why is assume(...) do_something();  gives an error when I run the code one more time, but do_something() assuming ...; do not give an error when everything else is the same?

Is there semantic difference between the two forms? I thought they should work the same way. Here is an example

#in separate cell
restart;

#in separate cell
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
assume(x>0);assume(t>0);assume(k>0):
sol:= pdsolve({pde,ic,bc},u(x,t)):

#in separate cell. Now this gives error
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
assume(x>0);assume(t>0);assume(k>0):
sol:= pdsolve({pde,ic,bc},u(x,t)):
#error message now

Here is screen shot

Now will do the same, but use assuming. Now there is no error

#in one cell
restart;

#in one cell
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
sol:= pdsolve({pde,ic,bc},u(x,t)) assuming x>0,t>0,k>0:

#in one cell, no error
interface(showassumed=0):
pde := diff(u(x, t), t)=k*diff(u(x, t), x$2):
ic:=u(x,0)=0: bc:=u(0,t)=t:
sol:= pdsolve({pde,ic,bc},u(x,t)) assuming x>0,t>0,k>0:

Here is screen shot

Why does one give an error, but the second one does not?

I thought they work the same way. Which method is recommended to use?

assume(...); do_something(); 

or 

do_something() assuming ...;

Maple 2018 on windows.