Some of the subdirectories in the ACME code contain code that was brought in from another repository. List them all.

external any subdirectory in ACME whose entire content is from another repository
upstream master the repository everyone is sending their changes to. Only one so that everyone pulling from the same source is working with all the same changes. The source of an external.

Methods for including externals

submodule a link that points to another git repository. See Sharing External Code using Git Submodules . Submodules require an extra step after cloning to get the code.
subtree a set of files and commits from another git repo, brought in to your repo. See Sharing External Code using Git Subtree. Subtrees are included in ACME when you "git clone".
monorepo adding multiple projects, related or not, in the same repo.
buildtime the repo is checked out to the $CIME_OUTPUT_ROOT/$CASE/bld when compiling a case for the first time. Code does not exist in ACME repo.

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Rules for adding externals

Group leads must approve adding a new external. The group needing the external can decide on the method of inclusion. A POC for the upstream master must be identified and the SE group leads notified.
The upstream master for the external must be build-able and testable on its own.
For submodules, the linked repo must be readable by all ACME developers. If the upstream master can not be made readable, a clone must be maintained in ACME-Climate github and ACME then links to that clone

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Subdirectory in ACME	external method	upstream master	development method	POC	Notes
CICE column physics?

Code location:  ACME/cime

Any code development in ACME/cime/config/acme can be committed directly to ACME through the normal PR process.

Code development in other parts of CIME should be committed first with a PR in https://github.com/ESMCI/cime. It will be then brought to ACME by a subtree merge as in Maintaining the CIME subtree in ACME.

ACME staff can report any bugs in CIME at https://github.com/ACME-Climate/ACME/issues. SE/CPL staff may open a companion report at https://github.com/ESMCI/cime/issues. ACME cime bugs which have been fixed in ESMCI and are waiting a subtree merge will have the github label "Fixed in ESMCI" attached to them.