SYSML17 — Deprecate Unit and QuantityKind stereotypes in 1.4

Instead of deleting the Unit and QuantityKind stereotypes according to the 18269 resolution in SysML 1.4 ballot 4, I suggest moving these stereotypes to the SysML::DeprecatedElements package.

Without doing this, a SysML 1.4 tool that opens a SysML 1.3 model will have to convert InstanceSpecifications stereotyped by SysML 1.3 Unit or QuantityKind into InstanceSpecifications classified by SysML::Libraries::UnitAndQuantityKind::Unit or QuantityKind respectively.

Even if a SysML 1.4 tool alerts the user that this migration has happened, it will not be possible to discern InstanceSpecifications classified by SysML::Libraries::UnitAndQuantityKind::Unit or QuantityKind due migration from SysML 1.3 vs. deliberate choice.

A better migration strategy would be to convert SysML 1.3 Unit/QuantityKind-stereotyped InstanceSpecifications into SysML 1.4 InstanceSpecifications that are both:
stereotyped by SysML::DeprecatedElements::Unit/QuantityKind
Classified by SysML::Libraries::UnitAndQuantityKind::Unit or QuantityKind
The former leaves a persistent indication that the InstanceSpecifications have been partially migrated.
The latter represents a partial migration to SysML 1.4 Units/QuantityKinds; that is, the user can complete the migration by classifying these InstanceSpecifications with concrete SysML Blocks that specialize SysML::Libraries::UnitAndQuantityKind::Unit or QuantityKind respectively.

Proposal: Deprecate Unit and QuantityKind stereotypes in 1.4

The issue asked for another solution than voted in a ballot for SysML 1.4. It is too late for this issue since the model elements were deleted in SysML 1.4.