Layer order and arranging layers

Revision as of 23:44, 11 December 2006

Layer stack is an ordered set of layers. Layer's position in the stack reflects to the topic resolution in Wandora. Layer order in the stack has an effect to the topics and associations in Wandora. General rule is that a topic inherits properties from the top layer consisting the topic property. Top property overlays all other properties in lower layers.

Lets say we have two layers in Wandora, layer1 and layer2. Both layers contain a topic with subject identifier of http://www.wandora.net/Finland describing our home country Finland. Due to merge rule these two topics merge in Wandora. Now lets assume that both topics have different base name. Topic in layer1 has a base name Suomi while the topic in layer layer2 has a base name Finland. Both are valid base names and the question is which base name should Wandora use for the merged topic? Remember that topics may contain only one unscoped base name in Wandora. The answer to the question lies in the order of layer1 and layer2. When layer1 is above layer2 merged topic has base name Suomi and when the layer1 is below the layer2 merged topic has base name Finland. This applies not only to base names but also variant names and occurrences of same type and scope.

Analogy drawn earlier between the layer concept of Wandora and graphic design applications may lighten the effect of layer order also. In graphic design applications the graphic element in top layer overlays the elements in lower layers. Similarly the base name in Wandora's top layer overlays base name's of merged topics in lower layers. Similarly the occurrence text of top layer overlays the occurrence of merged topics in lower layers.

To arrange layer order in the stack you can

• Drag and drop layers.
• Use submenus in Layers > Arrange layers.