Change:
This PR contains corrections to more accurate expression. This PR does not contains modification related to backwards compatibility and interoperability.
Thanks Sean I approved all above modifications.

Discussion:
RFC5280 specifies several extended key usages for X.509 certificates. This document defines a general purpose document signing extended key <del> usage for X.509 public key certificates which restricts the usage of </del> <ins> usage for X.509 public key certificates which specifies the usage of </ins> the certificates for document signing. 1. <del> RFC5280 specifies several extended key usages for X.509 certificates. In addition, several extended key usage had been addedRFC7299 as public OID under the IANA repository.  While usage of any extended key usage is bad practice for publicly trusted certificates, there are no public and general extended key usage explicitly assigned for Document Signing certificates.  The current practice is to use id-kp- emailProtection, id-kp-codeSigning or vendor defined Object ID for general document signing purposes. </del> <ins> RFC5280 specifies several extended key purpose identifiers for X.509 certificates.  In addition, several extended key purpose identifiers were addedRFC7299 as public OIDs under the IANA PKIX Extended key purpose identifiers arc.  While usage of the any extended key usage value is bad practice for publicly trusted certificates, there is no public and general extended key purpose identifier explicitly assigned for Document Signing certificates.  The current practice is to use id-kp-emailProtection, id-kp-codeSigning or vendor defined Object IDs for general document signing purposes. </ins> In circumstances where code signing and S/MIME certificates are also widely used for document signing, the technical or policy changes

Therefore, it is not favorable to use a vendor defined EKU for signing a document that is not governed by the vendor. <del> This document defines a general Document Signing extended key usage. </del> <ins> This document defines a general Document Signing extended key purpose identifier. </ins> 2.

This specification defines the KeyPurposeId id-kp-documentSigning. Inclusion of this KeyPurposeId in a certificate indicates that the <del> use of any Subject names in the certificate is restricted to use by a document signing. </del> <ins> use of the certified public key is allowed to be used for verifying the signature on a document. </ins> <del> Term of "Document Sign" in this document is digitally sign contents </del> <ins> Term of "Document Sign" in this document is digitally signes contents </ins> that are consumed by humans.  To be more precise, contents are intended to be shown to human with printable or displayable form by means of services or software, rather than processed by machines.

This specification defines the KeyPurposeId id-kp-documentSigning. Inclusion of this KeyPurposeId in a certificate indicates that the <del> use of any Subject names in the certificate is restricted to use by a document signing service or a software (along with any usages allowed by other EKU values). </del> <ins> Subject named in the certificate signed the document content, and the associated keys can be used by a document signing service or a software for authentication, message integrity, and non-repudiation of origin (using digital signatures, along with any usages allowed by other EKU values). </ins> 4.

The signed contents of Internet-Drafts are primarily intended to be consumed by human.  To be more precise, contents are intended to be shown to human in a printable or displayable form by means of <del> services or software, rather than processed by machines.  To validate the digital signature which is signed to contents intended to be consumed by human, implementations MAY perform the steps below as a certificate validation: </del> <ins> services or software, rather than processed by machines.  The digital signature on the contents is to indicate to the recipient of the contents that the content has not changed since it was signed by the identity indicated as the subject of the certificate.  To validate the digital signature which is signed on contents intended to be consumed by humans, implementations MAY perform the steps below during certificate validation: </ins> The implementation MAY examine the Extended Key Usage value(s):

The procedure is intended to permit or prohibit presence of a certain EKU or complete absence of EKUs.  It is outside the scope of this <del> document, but the relying party can permit or prohibit conbinations of EKU.  A consideration on prohibiting combination of EKUs is </del> <ins> document, but the relying party can permit or prohibit combinations of EKU.  A consideration on prohibiting combinations of EKUs is </ins> described in the security consideration section of this document. 2.1.  Excluded EKUs procedure "Excluded EKU" is an EKU which the

restriction, the certificate is acceptable.  Otherwise, relying party or the relying party software rejects the certificate. <del> When a single software has capability to process various data </del> <ins> When a single software has the capability to process various data </ins> formats, the software may choose to make the excluded and permitted decisions separately in accordance with the format it is handling (e.g. text, pdf, etc).

6. <del> The usage of id-kp-documentSigning EKU intends to prevent id-kp- emailProtection from being used for none-email purposes and id-kp- codeSigning used to sign objects other than binary codes.  This EKU does not introduce new security risks but instead reduces existing security risks by providing means to separate other EKUs used for communication protocols namely, TLS or S/MIME etc. in order to minimize the risk of cross protocol attacks. </del> <ins> The usage of id-kp-documentSigning EKU is to provide an alternative to id-kp-emailProtection being used for non-email purposes and id-kp- codeSigning being used to sign objects other than binary code.  This EKU does not introduce new security risks but instead reduces existing security risks by providing means to separate other EKUs used for communication protocols namely, TLS or S/MIME etc. in order to minimize the risk of cross protocol attacks. </ins> To reduce the risk of specific cross protocol attacks, the relying <del> party or relying party software may additionaly prohibit use of </del> <ins> party or relying party software may additionally prohibit use of </ins> specific combination of EKUs. While a specific protocol or signing scheme may choose to come up <del> with their own EKU, some may not have significant motive or resource to set up and manage thier own EKU.  This general document signing </del> <ins> with their own EKU, some may not have significant motive or resources to set up and manage their own EKU.  This general document signing </ins> EKU may be used as a stop gap for those that intend to set up their own EKU or those who do not intend to set up an EKU but still would <del> like to distinguish from other usage. </del> <ins> like to distinguish document signing from other usages. </ins> Introduction of this id-kp-documentSigning EKU value does not introduce any new security or privacy concerns.