The Solr 4 spatial code introduced a custom format for a rectangle and a Circle. In 4.3, it was deprecated in favor of WKT, which no longer required JTS for WKT parsing. It should be removed now. The syntax is governed by LegacyShapeReadWriterFormat (Spatial4j) referenced by Solr's AbstractSpatialFieldType.parseShape.
Examples of the syntax to be removed are as follows:
- Rect: -74.093 41.042 -69.347 44.558
- Circle: Circle(4.56,1.23 d=0.0710)
In addition to use in indexing & querying, the rect shape is also found in the worldBounds attribute (optional, only required if you use geo=false)