diff --git a/lib/doc/languages/gf-english-1.txt b/lib/doc/languages/gf-english-1.txt
index df410382e..8a4862c9a 100644
--- a/lib/doc/languages/gf-english-1.txt
+++ b/lib/doc/languages/gf-english-1.txt
@@ -1,4 +1,58 @@
 
 +Words: English-specific rules+
 
+++Morphological features++
+
+The first task when defining the language-specific rules for linguistic structures in the RGL is to give the
+actual ranges of the features attached to the categories. We have to tell whether the language has the grammatical
+number (as e.g. Chinese has not), and which values it takes (as many languages have two numbers but e.g. Arabic has three).
+We have to do likewise for case, gender, person, tense - in other words, to specify the **parameter types** of
+the language. Then we have to proceed to specifying which features belong to which lexical categories and how (i.e.
+as inflectional or inherent features). In this process, we may also note that we need some special features that
+are complex combinations of the "standard" features (as happens with English verbs: their forms are depend on tense,
+number, and person, but not as a straightforward combination of them). We may also notice that a "words" in some 
+category may in fact consist of several words, which may even appear separated from each other. English verbs such as
+//switch off//, called **particle verbs**, are a case in point. The particle contributes essentially to the meaning
+of the verb, but it may be separated from it by an object: //Please switch it off!//
+
+
+===Table: parameter types needed for content words in English===
+
+|| GF name   | text name | values             ||
+| ``Number`` | number    | singular, plural
+| ``Person`` | person    | first, second, third
+| ``Case``   | case      | nominative, genitive
+| ``Degree`` | degree    | positive, comparative, superlative
+| ``VForm``  | verb form | infinitive, present, past, past participle, present participle
+
+
+The assignment of parameter types and the identification of the separate parts of categories defines a
+the **data structures** in which the words are stored in a lexicon.
+This data structure is in GF called the **linearization type** of the category. From the computational
+point of view, it is important that the data structures are well defined for all words, even if this may
+sound unnecessary. For instance, since some verbs need a particle part, all verbs must uniformly have a
+storage for this particle, even if it is empty most of the time. This property is guaranteed by
+an operation called **type checking**. It is performed by GF as a part of **grammar compilation**, which
+is the process in which the human-readable description of the grammar is converted to bits executable
+by the computer.
+
+
+===Table: linearization types of English content words===
+
+|| GF name  | text name        | example    | inflectional features       | inherent features  ||
+| ``N``     | noun             | //house//  | number, case                | (none)         
+| ``PN``    | proper name      | //Paris//  | case                        | (none)
+| ``A``     | adjective        | //blue//   | degree                      | (none)
+| ``V``     | verb             | //sleep//  | verb form                   | particle
+| ``Adv``   | adverb           | //here//   | (none)                      | (none)
+| ``V2``    | two-place verb   | //love//   | verb form                   | particle, preposition
+| ``VV``    | verb-complement verb   | //try//   | verb form              | particle, infinitive form
+| ``VS``    | sentence-complement verb   | //know//   | verb form              | particle
+| ``VQ``    | question-complement verb   | //ask//    | verb form              | particle
+| ``VA``    | adjective-complement verb  | //become// | verb form              | particle
+
+Notice that we have placed the particle of verbs in the inherent feature column. It is not a parameter
+but a string. 
+We have done the same with the preposition strings that define the complement features of verb 
+and other subcategories.
 
diff --git a/lib/doc/languages/gf-general-1.txt b/lib/doc/languages/gf-general-1.txt
index 656180073..8d518ed16 100644
--- a/lib/doc/languages/gf-general-1.txt
+++ b/lib/doc/languages/gf-general-1.txt
@@ -298,6 +298,12 @@ of a uniform class of pronouns, as we did with the verb subcategories: for verbs
 set of features, to which only complement feature information had to be added, but the same does not concern the things
 traditionally called "pronouns".
 
+Structural words moreover contain many categories that have no morphological variation or morphologically relevant features.
+For instance, interrogative adverbs (such as //why//) and sentential adverbs (such as //always//) are, in all languages we
+have encountered, equivalent from the morphological point of view. Yet of course they are syntactically different, as
+one cannot convert //why are you always late// into //always are you why late//. And semantically, sentential adverbs
+modify actions whereas interrogative adverbs form questions from sentences.
+
 The following tables give a summary of the structural word categories of the RGL, equipped with morphological and
 semantic information as we did for content words. The full details will be best explained in the sections on syntax,
 i.e. on how the structural words are actually used for building structures.