The presentation of this document has been augmented to identify changes from a previous version. Three kinds of changes are highlighted: ↑new, added text↑,↑changed text↓, and↓deleted text↓.
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1 Introduction
2 Changes to Constraints on Components
3 Changes to Validation Rules
Making wildcards 'weaker' than explicit declarations removes much of the perceived negative impact of UPA, considerably increasing their utility wrt versioning
Fortunately implementing the change to wildcard semantics can be done gracefully at the level of abstraction already adopted in 1.0, while at the same time giving a more explicit definition of (what remains of) UPA than was done in 1.0.
[Definition:] Define a partition of a sequence as a sequence of sub-sequences, some or all of which may be empty, such that concatenating all the sub-sequences yields the original sequence.↑[Definition:] Define the set of component sequences assigned to a sequence of element information items by a [weak] model group as follows:↑ the appropriate case among the following:Editorial Note: The following definitions are moved from their former home in Element Sequence Valid
n
sub-sequences where n
is the length of {particles} such that each of the sub-sequences in order is ·valid·
with respect to the corresponding particle in the {particles} as defined in (§)↑, the sequence of ·context-determined
components· as determined for each member of the item sequence by (§) is a member of the ·set of component sequences assigned· to the item sequence by the group↑.n
sub-sequences where n
is the length of {particles} such that there is a one-to-one mapping between the sub-sequences and the {particles} where each sub-sequence is ·valid· with respect to the corresponding particle as defined in (§)↑, the sequence of ·context-determined
components· as determined for each member of the item sequence by (§) is a member of the ·set of component sequences assigned· to the item sequence by the group↑.