Update content

src/pages/api/parameters/layering_declare_stacks.md

@@ -38,6 +38,7 @@ keywords:
 Material layering: declare editable stacks
 ==========================================
 
+-
 
 An editable stack is defined by a unique identifier and a list of document channels.
  Possible channel id(s) are:
@@ -145,8 +146,8 @@ To bind a channel from a stack to a sampler parameter, prefix the channel tag wi
  uniform sampler2D mask_tex1;
  //: param auto Mask2.channel_opacity
  uniform sampler2D mask_tex2;
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- 
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+
 ```