Currently, there is no good way to use the “Generate” button in the item record to create descriptions for supplements and indexes. In the interest of consistency, we intentionally do NOT enter the descriptions manually, which greatly improves searching and sorting of serials.
While it is possible to have supplements and indexes list separately by creating separate records and adding the $o (unit title) to field 864 (supplements) or 865 (indexes), the holdings list does not display the unit title, so there is no visual difference between the two holdings. An 863 holding for “Aperture” and an 864 holding for “The Photobook Review” would appear identical in the list of holdings. This would also list the supplements separately from the issue to which they are a supplement in both Alma and Primo, which is undesirable. Furthermore, all holdings still draw upon the same description template table for generation of the description, which is the most useful field for distinguishing serial issues in Alma and Primo.
At present, there is no equivalent to MARC holdings 863-865 subfield $o in the item record. (Nor is there a field for subfields n, p, or q, but I personally haven’t had a need for them as yet). In order to get the supplement title to display, it must be improperly entered into one of the enumeration fields. However, those are fields legitimately in use with other data, so any description templates must take into account both legitimate and “work around” uses for the field(s). It is virtually impossible to account for all possible values which could be used in an enumeration field, since volume numbers and issue numbers can continue indefinitely and supplement titles may differ with each issuance. Likewise, use of the generic title “supplement” is less than helpful where multiple supplements are issued (i.e. The New York Times)
For example, right now I cannot set up a description template to simply display the text as input in $b, since most serial issues need to have that field prefixed with “no.” and I want that constant as part of the generated description coded in the template. If I just put the supplement title in $b and use the template as it works best for most issues, I get a display like “v.103:no.Book Review(Aug. 8 2016)”

Adding a unit title field to the item record and including it in the generated description seems as though it would be the most efficient solution to this problem, at least from the perspective of the person receiving the issues. Supplement titles, index notation, etc., could then be placed in this field and its display could be defined in description templates without having to account for the field’s use as a volume or issue number. Using this approach would also, in theory, enable reporting, searching, and sorting supplements and indexes both with the basic units (by using the description field) or separate from them (by using the separate fields that make up the description).
An alternate solution could be to add radial buttons to the item record indicating whether they a basic unit, a supplement, or an index and then add corresponding radial buttons to the description templates to indicate if it is applicable to one, some, or all of those issue types. In this way, I could have two templates utilizing exactly the same combination of enumeration and chronology fields, but define one to add the “no.” prefix and one to skip it. This, however, seems like a poor form, since the enumeration fields, by their very name, are designed to hold numeric data, not text. This also limits ability to report and sort supplements and indexes separately from the basic unit, since there is no distinct subfield.