Display alternate graphic (880) fields
======================================

By default, Evergreen displays alternate graphic fields, if any, for
contributors (1xx / 7xx), titles (245), edition statements (250), imprints
(260), notes (5xx), subjects (6xx), and series (4xx / 8xx) in search results and record details
per the Library of Congress MARC21 specifications:

* http://www.loc.gov/marc/bibliographic/bd880.html
* http://www.loc.gov/marc/bibliographic/ecbdcntf.html
* http://www.loc.gov/marc/bibliographic/ecbdmulti.html (Model A)

Default display
---------------
In general, alternate graphic fields display below the corresponding
primary field. One exception is the attribution summary on the record details
page, in which the alternate graphic field contents display between the
primary field content and the attribution statement. To support CSS
customizations, HTML elements for the graphic fields have the class attribute
value `graphic880`.

Implementation details
----------------------
The template file `parts/misc_util.tt2` defines two macros for retrieving
linked 880 fields:

* `get_graphic_880s`: given a _target_field_ scalar value representing a MARC
  field tag, populate the _graphic_880s_ list with hashes containing the
  target field tag and any graphic fields linked to that particular tag, with
  the values for each being a simple concatenation of all subfields that are
  not control subfields (per
  http://www.loc.gov/marc/bibliographic/ecbdcntf.html). The structure of the
  `graphic_880s` list is as follows:
+
------------------------------------------------------------------------
[
    {
        "primary": {"occur": 01, "value": "foo foo"},
        "graphic": [
            {
                "occur": 01,
                "value": "bar bar",
                "orient": "rtl",
                "script": "CJK"
            }
        ]
    }
]
------------------------------------------------------------------------
* `get_linked_880s` macro iterates over the content of the `linked_fields`
  list, in which each element of the list to be a scalar representing the $6
  control subfield link info. The macro populates the `graphics` list with a
  set of graphic field hashes with the following structure:
+
------------------------------------------------------------------------
[
    {
        "occur": 01,
        "value": "bar bar",
        "orient": "rtl",
        "script": "CJK"
    }
]
------------------------------------------------------------------------

`misc_util.tt2` preserves legacy attribute lists to enable previous TPAC
customizations to continue to function normally.