diff --git a/extensions/openpower-pels/README.md b/extensions/openpower-pels/README.md
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+++ b/extensions/openpower-pels/README.md
@@ -43,4 +43,7 @@
 
 ## The PEL Message Registry
 
+The PEL message registry is used to create PELs from OpenBMC event logs.
+Documentation can be found [here](registry/README.md).
+
 ## D-Bus Interfaces
diff --git a/extensions/openpower-pels/registry/ComponentIDs.md b/extensions/openpower-pels/registry/ComponentIDs.md
new file mode 100644
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@@ -0,0 +1,9 @@
+# PEL Component ID List
+
+See [here](README.md#component-ids) for details on how PEL component IDs are
+used.
+
+| Component ID | Repository |
+|--------------|------------|
+| 0x1000       | Common Errors that span repositories |
+| 0x2000       | phosphor-logging |
diff --git a/extensions/openpower-pels/registry/README.md b/extensions/openpower-pels/registry/README.md
new file mode 100644
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+# Platform Event Log Message Registry
+On the BMC, PELs are created from the standard event logs provided by
+phosphor-logging using a message registry that provides the PEL related fields.
+The message registry is a JSON file.
+
+## Contents
+* [Component IDs](#component-ids)
+* [Message Registry](#message-registry-fields)
+
+## Component IDs
+A component ID is a 2 byte value of the form 0xYY00 used in a PEL to:
+1. Provide the upper byte (the YY from above) of an SRC reason code in `BD`
+   SRCs.
+2. Reside in the section header of the Private Header PEL section to specify
+   the error log creator's component ID.
+3. Reside in the section header of the User Header section to specify the error
+   log committer's component ID.
+4. Reside in the section header in the User Data section to specify which
+   parser to call to parse that section.
+
+Component IDs are specified in the message registry either as the upper byte of
+the SRC reason code field for `BD` SRCs, or in the standalone `ComponentID`
+field.
+
+Component IDs will be unique on a per-repository basis for errors unique to
+that repository.  When the same errors are created by multiple repositories,
+those errors will all share the same component ID.  The master list of
+component IDs is [here](ComponentIDs.md).
+
+## Message Registry Fields
+The message registry schema is [here](schema/schema.json), and the message
+registry itself is [here](message_registry.json).  The schema will be validated
+either during a bitbake build or during CI, or eventually possibly both.
+
+In the message registry, there are fields for specifying:
+
+### Name
+This is the key into the message registry, and is the Message property
+of the OpenBMC event log that the PEL is being created from.
+
+```
+"Name": "xyz.openbmc_project.Power.Fault"
+```
+
+### Subsystem
+This field is part of the PEL User Header section, and is used to specify
+the subsystem pertaining to the error.  It is an enumeration that maps to the
+actual PEL value.
+
+```
+"Subsystem": "power_supply"
+```
+
+### Severity
+This field is part of the PEL User Header section, and is used to specify
+the PEL severity.  It is an optional field, if it isn't specified, then the
+severity of the OpenBMC event log will be converted into a PEL severity value.
+
+```
+"Severity": "unrecoverable"
+```
+
+### Mfg Severity
+This is an optional field and is used to override the Severity field when a
+specific manufacturing isolation mode is enabled.
+
+```
+"MfgSeverity": "unrecoverable"
+```
+
+### Event Scope
+This field is part of the PEL User Header section, and is used to specify
+the event scope, as defined by the PEL spec.  It is optional and defaults to
+"entire platform".
+
+```
+"EventScope": "entire_platform"
+```
+
+### Event Type
+This field is part of the PEL User Header section, and is used to specify
+the event type, as defined by the PEL spec.  It is optional and defaults to
+"not applicable".
+
+```
+"EventType": "na"
+```
+
+### Action Flags
+This field is part of the PEL User Header section, and is used to specify the
+PEL action flags, as defined by the PEL spec.  It is an array of enumerations.
+
+```
+"ActionFlags": ["service_action", "report", "call_home"]
+```
+
+### Mfg Action Flags
+This is an optional field and is used to override the Action Flags field when a
+specific manufacturing isolation mode is enabled.
+
+```
+"MfgActionFlags": ["service_action", "report", "call_home"]
+```
+
+### Component ID
+This is the component ID of the PEL creator, in the form 0xYY00.  For `BD`
+SRCs, this is an optional field and if not present the value will be taken from
+the upper byte of the reason code.  If present for `BD` SRCs, then this byte
+must match the upper byte of the reason code.
+
+```
+"ComponentID": "0x5500"
+```
+
+### SRC Type
+This specifies the type of SRC to create.  The type is the first 2 characters
+of the 8 character ASCII string field of the PEL.  The allowed types are `BD`,
+for the standard OpenBMC error, and `11`, for power related errors.  It is
+optional and if not specified will default to `BD`.
+
+Note: The ASCII string for BD SRCs looks like: `BDBBCCCC`, where:
+* BD = SRC type
+* BB = PEL subsystem as mentioned above
+* CCCC SRC reason code
+
+For `11` SRCs, it looks like: `1100RRRR`, where RRRR is the SRC reason code.
+
+```
+"Type": "11"
+```
+
+### SRC Reason Code
+This is the 4 character value in the latter half of the SRC ASCII string.  It
+is treated as a 2 byte hex value, such as 0x5678.  For `BD` SRCs, the first
+byte is the same as the first byte of the component ID field in the Private
+Header section that represents the creator's component ID.
+
+```
+"ReasonCode": "0x5544"
+```
+
+### SRC Symptom ID Fields
+The symptom ID is in the Extended User Header section and is defined in the PEL
+spec as the unique event signature string.  It always starts with the ASCII
+string.  This field in the message registry allows one to choose which SRC words
+to use in addition to the ASCII string field to form the symptom ID. All words
+are separated by underscores.  If not specified, the code will choose a default
+format, which may depend on the SRC type.
+
+For example: ["SRCWord3", "SRCWord9"] would be:
+`<ASCII_STRING>_<SRCWord3>_<SRCWord9>`, which could look like:
+`B181320_00000050_49000000`.
+
+```
+"SymptomIDFields": ["SRCWord3", "SRCWord9"]
+```
+
+### SRC words 6 to 9
+In a PEL, these SRC words are free format and can be filled in by the user as
+desired.  On the BMC, the source of these words is the AdditionalData fields in
+the event log.  The message registry provides a way for the log creator to
+specify which AdditionalData property field to get the data from, and also to
+define what the SRC word means for use by parsers.  If not specified, these SRC
+words will be set to zero in the PEL.
+
+```
+"Words6to9":
+{
+    "6":
+    {
+        "description": "Failing unit number",
+        "AdditionalDataPropSource": "PS_NUM"
+    }
+}
+```
+
+### SRC Power Fault flag
+The SRC has a bit in it to indicate if the error is a power fault.  This is an
+optional field in the message registry and defaults to false.
+
+```
+"PowerFault: false
+```
+
+### Documentation Fields
+The documentation fields are used by PEL parsers to display a human readable
+description of a PEL.  They are also the source for the Redfish event log
+messages.
+
+#### Message
+This field is used by the BMC's PEL parser as the description of the error log.
+It will also be used in Redfish event logs.  It supports argument substitution
+using the %1, %2, etc placeholders allowing any of the SRC user data words 6 -
+9 to be displayed as part of the message.  If the placeholders are used, then
+the `MessageArgSources` property must be present to say which SRC words to use
+for each placeholder.
+
+```
+"Message": "Processor %1 had %2 errors"
+```
+
+#### MessageArgSources
+This optional field is required when the Message field contains the %X
+placeholder arguments. It is an array that says which SRC words to get the
+placeholders from.  In the example below, SRC word 6 would be used for %1, and
+SRC word 7 for %2.
+
+```
+"MessageArgSources":
+[
+    "SRCWord6", "SRCWord7"
+]
+```
+
+#### Description
+A short description of the error.  This is required by the Redfish schema to generate a Redfish message entry, but is not used in Redfish or PEL output.
+
+```
+"Description": "A power fault"
+```
+
+#### Notes
+This is an optional free format text field for keeping any notes for the
+registry entry, as comments are not allowed in JSON.  It is an array of strings
+for easier readability of long fields.
+
+```
+"Notes": [
+    "This entry is for every type of power fault.",
+    "There is probably a hardware failure."
+]
+```