Using-the-pycrate-asn1-runtime.md

@@ -419,9 +419,8 @@ of the object:
     }
 
 Here, only the first level of content is returned. The *get_proto()* method returns the complete
-content by entering each constructed content recursively. **Be careful** about some limitations of
-this method: its call on a recursive object will trigger a Python recursion exception... Moreover
-it does not provides hints on optional components (those marked OPTIONAL or with a DEFAULT value),
+content by entering each constructed content recursively. **Be careful** about the main limitation of
+this method: it does not provides hints on optional components (those marked OPTIONAL or with a DEFAULT value),
 neither on component in the root or extension part of the content.
 
     >>> SIC.get_proto()
@@ -449,6 +448,19 @@ neither on component in the root or extension part of the content.
      }
     }
 
+Regarding the mandatory or optional content of a constructed object, one can use the
+following attributes: *_root_mand*, *_root_opt* and *_ext*. The first lists all mandatory
+components from the root part: those need to be set with a value to conform to the ASN.1
+specification. The 2nd and 3rd list components that are OPTIONAL, have a DEFAULT value,
+or are in the extension part ; thus, they are all optional. This means you are not required
+to set them with a value to conform to the ASN.1 specification.
+
+    >>> SIC._root_mand
+    ['mib', 'sysInfoType1', 'sysInfoType3', 'sysInfoType5', 'sysInfoType7']
+    >>> SIC._root_opt
+    ['sysInfoTypeSB1', 'sysInfoTypeSB2', 'sysInfoType11', 'sysInfoType11bis', 'sysInfoType12', 'vb50NonCriticalExtensions']
+    >>> SIC._ext # this one is None, because System-Information-Container is not extensible
+
 Because the UMTS RRC protocol is using the UPER encoding, we will use the *from_uper()* 
 method to deserialize buffers. The corresponding value will be available in the *_val* attribute, 
 and will also be returned when calling the ASN.1 object itself. Finally, the *to_asn1()* 
@@ -508,8 +520,8 @@ radio interfaces: it saves bandwidth.
 As seen in the previous example, it is required to know the content of constructed objects
 to be able to access their internals, and also to be able to set values. Two utility functions
 are provided to help with that:
-- *get_obj_at(Obj, path)*
-- *get_val_at(Obj, path)*
+- *get_at(Obj, path)* to navigate within an ASN.1 object
+- *get_val_at(Obj, path)* to navigate within the value assigned to an ASN.1 object
 
 Both take an ASN.1 object and the path to one of its internal component or value and return it.
 Here are some examples with the previous *PCCH_Message* object:
@@ -524,7 +536,7 @@ Here are some examples with the previous *PCCH_Message* object:
      spare: 'NULL'
      }
     }
-    >>> get_obj_at(pcch, ['message', 'pagingType1', 'pagingRecordList', None, 'utran-Identity'])
+    >>> get_at(pcch, ['message', 'pagingType1', 'pagingRecordList', None, 'utran-Identity'])
     <utran-Identity (SEQUENCE)>
     >>> # pagingRecordList being a SEQUENCE OF, no need to provide any name to select its content
     >>> get_val_at(pcch, ['message', 'pagingType1', 'pagingRecordList', 2])
@@ -1326,9 +1338,9 @@ and re-encoding an InitialDP operation CAP message, that is handled by the ASN.1
     >>> get_val_at(M, ['begin', 'components', 0, 'basicROS', 'invoke', 'argument', 'InitialDPArg', 'locationInformation'])
     {'vlr-number': b'\x913f\x02\x00\x00\xf0', 'cellGlobalIdOrServiceAreaIdOrLAI': ('cellGlobalIdOrServiceAreaIdFixedLength', b'1234567')}
     >>> # let's modify the locationInformation
-    >>> get_obj_at(M, ['begin', 'components', 0, 'basicROS', 'invoke', 'argument', 'InitialDPArg', 'locationInformation', 'cellGlobalIdOrServiceAreaIdOrLAI'])
+    >>> get_at(M, ['begin', 'components', 0, 'basicROS', 'invoke', 'argument', 'InitialDPArg', 'locationInformation', 'cellGlobalIdOrServiceAreaIdOrLAI'])
     <cellGlobalIdOrServiceAreaIdOrLAI ([CellGlobalIdOrServiceAreaIdOrLAI] CHOICE)>
-    >>> get_obj_at(M, ['begin', 'components', 0, 'basicROS', 'invoke', 'argument', 'InitialDPArg', 'locationInformation', 'cellGlobalIdOrServiceAreaIdOrLAI'])._cont
+    >>> get_at(M, ['begin', 'components', 0, 'basicROS', 'invoke', 'argument', 'InitialDPArg', 'locationInformation', 'cellGlobalIdOrServiceAreaIdOrLAI'])._cont
     {
     cellGlobalIdOrServiceAreaIdFixedLength: <cellGlobalIdOrServiceAreaIdFixedLength ([CellGlobalIdOrServiceAreaIdFixedLength] OCTET STRING)>,
     laiFixedLength: <laiFixedLength ([LAIFixedLength] OCTET STRING)>