|  |  | ```mermaid | 
|  |  | sequenceDiagram | 
|  |  | olqv.js->>+serverWsgi: server is up ? | 
|  |  | serverWsgi->>olqv.js: yes | 
|  |  | olqv.js->>+serverWsgi: get rendering capabilities | 
|  |  | serverWsgi->>olqv.js: capabilities | 
|  |  | olqv.js->>+serverWsgi: get fits header | 
|  |  | serverWsgi->>olqv.js: header | 
|  |  |  | 
|  |  | alt path1 | 
|  |  | olqv.js->>+olqv.js: header declares 3D ? Yes | 
|  |  | olqv.js->>+olqv.ejs: display spectrum | 
|  |  | else path2: | 
|  |  | olqv.js->>+olqv.js: header declares 2D ? Yes | 
|  |  | olqv.js->>+olqv_2-5.ejs: display spectrum | 
|  |  | else path2: | 
|  |  | olqv.js->>+olqv.js: header declares another case ? Yes | 
|  |  | olqv.js->>+olqv_error.ejs: display spectrum | 
|  |  | end | 
|  |  | ``` | 
|  |  | \ No newline at end of file |