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+++ b/doc/Formatting-thoughts	Mon Mar 22 21:28:32 2021 +0000
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+Thoughts on card (re)formatting
+===============================
+
+ETSI and 3GPP specs give many more degrees of freedom to SIM card issuers than
+just the content of various EFs: the card issuer gets to decide which DFs and
+EFs will be present vs. which ones won't be present at all, and for many EFs
+the size (allocated space) is variable per the specs and up to the card issuer.
+In the case of record-based EFs, both the record size and the number of records
+are often left up to card issuers to tune as desired.
+
+In the Mother's opinion, a truly programmable SIM would be one where every
+downstream owner of each card (not just the initial factory or the party putting
+up big bucks for a large custom production run) can do a full reformat: erase
+the file system and then create whatever tree of DFs and EFs she desires, with
+full control over each file's allocated size, structure and access conditions.
+
+The problem, however, is that the people who work with big bucks and who control
+SIM card manufacturing have taken away our community's ability to freely
+reformat our programmable SIMs downstream of the factory.  To the best of our
+knowledge, there has only ever been one SIM card model in the entire history of
+Osmocom community that supported downstream reformatting, and this model was
+sysmoSIM-GR1:
+
+https://osmocom.org/projects/cellular-infrastructure/wiki/GrcardSIM
+
+But Grcard company no longer sells that original card model, and for their new
+card model (GrcardSIM2, branded sysmoSIM-GR2 or FCSIM1) there is no published
+documentation for how to erase the card file system and recreate it differently.
+We can only guess that this ability probably exists, but Grcard people are
+refusing to disclose the secret knowledge of how to do it unless we pay them
+some ginormous sum of money.
+
+The current offering from Sysmocom (sysmoISIM-SJA2) does not fare any better in
+this regard.  These cards are natively UICC, and in the world of UICC there
+exist partially standarized commands for creating and deleting files, defined in
+ETSI TS 102 222.  However, these commands are only partially standardized: the
+ETSI spec gives the general principles and the command structure, but many of
+the details as to exactly what needs to be put into the TLV structure fed to the
+CREATE FILE command in order for that command to succeed constitute proprietary
+knowledge.  Our experiments with this CREATE FILE command on sysmoISIM-SJA2 were
+unsuccessful.  The only way how the file structure of Sysmocom cards would
+become truly editable by end users would be if Sysmocom were to publish at least
+one fully worked-out example of a real CREATE FILE command that creates some
+dummy non-standard file just to prove it working, followed by a working example
+of a DELETE FILE command that deletes this newly created file, restoring the
+card to its original state.  However, we reason that Sysmocom would probably be
+willing to do this support work only if someone paid them for it on an hourly
+support basis, or ordered a large custom batch of cards from them and required
+this support knowledge as part of that deal - and we (FreeCalypso) are not
+currently in a position to pursue either of those two routes.