Alternate Structures

Often, a text is referred to using multiple overlapping schemes. In these cases, alternate structures may be specified on Index records. Two examples of this phenomenon are the Torah, which has both a chapter-verse addressing schema and a parashah-aliyah addressing schema, and the Talmud, which has both a daf addressing schema and a chapter-mishnah addressing schema.

If a text has multiple overlapping schemes, the text's storage format will be the structure that provides the greatest detail. This is specified in the schema attribute of the Index record. Other possible structures are specified in the alt_structs attribute of the text's Index record.

In short, alt_structs acts as a dictionary, mapping structure keys (which can be arbitrary) to alt structures. Alt structures look very much like the Index Schema but with a few key differences:

• The nodeType is generally ArrayMapNode
• The root node has no titles; instead, it uses the titles of the schema root.
• All nodes of the alt structure do not have key fields.
• Terminal nodes in an alternate structure have mappings to underlying references, using either one or both of the following attributes:
  • wholeRef: This single string has a ref to the whole range covered by the relevant node.
  • refs: This jagged array of refs corresponds to the way in which wholeRef is broken into sections, named by sectionNames. This attribute is only required when depth is greater than zero.
• Display attributes can be customized. This affects how an alternate structure is visualized in its Table of Contents. Customization options include:
  • includeSections: when True, the node will include links to each individual section within wholeRef underneath the alternate node name (e.g., Zohar).

For example: A section of the alternate structure of the book of Exodus

   "alt_structs" : {
        "Parasha" : {
            "nodes" : [ 
                {
                    "sharedTitle" : "Shemot",
                    "nodeType" : "ArrayMapNode",
                    "depth" : 1,
                    "sectionNames" : [ 
                       "Aliyah"
                    ],
                    "wholeRef" : "Exodus 1:1-6:1",
                    "refs" : [ 
                        "Exodus 1:1-1:17", 
                        "Exodus 1:18-2:10", 
                        "Exodus 2:11-2:25", 
                        "Exodus 3:1-3:15", 
                        "Exodus 3:16-4:17", 
                        "Exodus 4:18-4:31", 
                        "Exodus 5:1-6:1"
                    ],
                    "addressTypes" : [ 
                        "Integer"
                    ]
                }, 
                {
                    "sharedTitle" : "Vaera",
                    "nodeType" : "ArrayMapNode",
                    "depth" : 1,
                    "sectionNames" : [ 
                        "Aliyah"
                    ],
                    "wholeRef" : "Exodus 6:2-9:35",
                    "refs" : [ 
                        "Exodus 6:2-6:13", 
                        "Exodus 6:14-6:28", 
                        "Exodus 6:29-7:7", 
                        "Exodus 7:8-8:6", 
                        "Exodus 8:7-8:18", 
                        "Exodus 8:19-9:16", 
                        "Exodus 9:17-9:35"
                    ],
                    "addressTypes" : [ 
                        "Integer"
                    ]
                }, 
                {
                    "sharedTitle" : "Bo",
                    "nodeType" : "ArrayMapNode",
                    "depth" : 1,
                    "sectionNames" : [ 
                        "Aliyah"
                    ],
                    "wholeRef" : "Exodus 10:1-13:16",
                    "refs" : [ 
                        "Exodus 10:1-10:11", 
                        "Exodus 10:12-10:23", 
                        "Exodus 10:24-11:3", 
                        "Exodus 11:4-12:20", 
                        "Exodus 12:21-12:28", 
                        "Exodus 12:29-12:51", 
                        "Exodus 13:1-13:16"
                    ],
                    "addressTypes" : [ 
                        "Integer"
                    ]
                }, 
...