Need help with identification

Didn't know where to post this thread. So here it is.

What is the white "canvas" that appears in some Titanic photographs, and also in a few of ken Marshall's paintings? Over the open first class promenade on A-Deck. It appears to me like it's some kind of canvas or something? Here is a (bad)picture:

But it is not in every picture of the ship. Sorry for the bad picture. I know Ken marshall has a painting that shows this more clearly. I'll try and see if I can find it somewhere to show you what I am referring to
Found it! However, in very bad quality... I have combined two pictures to show the difference.

It appears as if, in Ken's Painting, the open promenade is less open near the enclosed promenade. However, I have only seen it in this KM painting and in the photo above, Therefore I assumed it was some kind of white canvas rolled up alongside the open promenade for some reason.
Hope you understand what I am referring to in this picture, though it is also in bad quality.

Hi Johan!

I "think" you can say canvas. I am not English so maybe I use the wrong word. (Will have a look).
These were used on the open parts of the A deck promenade as you can see on the picture. They were used as a protection against the weather and sun. Especially on bad weather. Olympic was having these too (like other ships).

Thanks Ioannis! That makes sense. But why were they only visible sometimes? Did they take them down and put them in storage rooms on the ship when they weren't used, or did they hang rolled up to the A Deck promenade ceiling? Some more info would be great, but thanks anyway!
Hi Johan!

First, yes canvas is the right word! :)
Now to your questions. The canvas were not always visible. The picture you add for example show Titanic in Queenstown. Most likely they were used there as a protection against the glare of the morning sun.
In very bad weather they would have been rolled completely down as it was done on Olympic.
Your last question is a little difficult. I am not 100 % sure but they must have been on the deck head. Maybe I am wrong on that point. I know this was done on Olympic but the picture I saw were from the 1920s.
Maybe someone else knew more?!