Bản mẫu:Harvc/doc

This template is a citation hybrid that has characteristics of the long-form cs1 and cs2 and characteristics of short-form sfn and the harv families of templates. Its purpose is to provide a method that allows editors to refer to a contribution or chapter in a larger work when more than a few such referrals are required.  harvc is not a substitute for a properly constructed citation.
Short-form templates sfn and harv are often used to link from an article's references section to a long-form cs1|2 template in a bibliography section:
sfn → cite book
It is not uncommon for a source have multiple contributors.  When it is necessary to refer to multiple contributions in the same source, repeating all of the bibliographic details in multiple long-form citation templates adds to references-section clutter.  harvc is designed to hold only the detail necessary to identify a contribution and link to the enclosing work's long-form citation where all of the bibliographic detail can be found:
sfn → harvc → cite book

**Cách sử dụng**
The minimal form is:

According to the comments in Module:Harvc, mistaken Harvc error: no target: error messages may be produced when the template is nested in other templates as on documentation pages. The otherwise undocumented parameter, yes, can be added to prevent this.

**Parameters**
creates a CITEREF anchor from one to four contribution or chapter author surnames (lastn) and the value in year. This allows harvc to be the target of a link created by sfn or harv family templates.  From  and year, harvc creates a CITEREF link similar to those created by Harvard citation no brackets and sfn
 |anchor-year= – optional, for use for author(s) with more than one contribution to the work; requires CITEREF disambiguator; see Examples
 |author-link= – optional, title of existing Wikipedia article about the first contributor—not the contributor's website; do not wikilink; alias: |author-link1=
: |author-linkn= – optional, title of existing Wikipedia article about contributorn; choose n to match n in |lastn=
 |author-mask=m – optional, replaces name of the first contributor with m (commonly 2) em dashes; alias: |author-mask1=
: |author-maskn=m – optional, replaces name of contributorn with m em dashes; choose n to match n in |lastn=
: |author-maskn= – optional, replaces name of contributorn with 
 |c= – required, the title of chapter or contribution; rendered quoted in upright font; aliases: |chapter=, |contribution=
 |trans-c= – the translated title of chapter or contribution; rendered in square brackets; aliases: |trans-chapter=, |trans-contribution=
 |display-authors= – optional, defines how harvc displays the contributor list; ignored when |name-list-style=harv:
: display-authors – when empty or omitted, displays all contributor names in last/first format
:  – displays n contributor names in last/first format; appends et al. when n is less than the number of contributors included in the template
: etal – displays all contributor names in last/first format and appends et al.
 |first= – optional, first contributor's given or first name; alias: |first1=
: |firstn= – optional, contributorn given or first name; n begins at 2 and increases by 1 for each additional |firstn=
 |id= – required when last1-last4 are the same as in1-in4; otherwise optional.  See Examples
 |in= – required, surname or last name of first editor or author of the work that includes the contribution; aliases: |in1=
 |in2= – optional, surname or last name of second editor or author
 |in3= – optional, surname or last name of third editor or author
 |in4= – optional, surname or last name of fourth editor or author
 |last= – required, surname or last name of first author; aliases: |last1=
: |lastn= – optional, contributorn surname or last name; n begins at 2 and increases by 1 for each additional |lastn=;
 |loc= – optional, other location identifier, displays after p or pp
 |mode= – controls rendered display to match that of adjacent CS1 or CS2 citations; defaults to CS1 style
: |mode=cs2 – mimic citation style (comma separators, no terminal punctuation, static text not capitalized)
 |name-list-style= – optional, controls contributor name list display style
: |name-list-style=harv – mimic sfn or harv format (one to four last names); overrides |display-authors=
: |name-list-style=amp – inserts an ampersand between the last two contributor names
 |nb= – optional, when set to yes, instructs harvc to render source link without parentheses around the year; same format as that produced by Harvard citation no brackets
 |p= – optional, single page number where cited material can be found; aliases: |page=
 |pp= – optional, multiple page numbers, page ranges, etc where cited material can be found; aliases: |pages=
 |ps= – optional, sets terminal punctuation; default is full stop; overrides |mode=cs2; aliases: |postscript=
: |ps=none – renders output without terminal punctuation
 |url= – optional, URL of an online location where the text of the contribution can be found; aliases: |chapter-url, |contribution-url
 |url-access= – optional, use when URL links to a source behind a registration barrier or paywall; inserts cs12 access icon; accepted values are: limited, registration, subscription
 |year= – required, publication year of the work that includes the contribution

**Examples**
When a Wikipedia article makes reference to a work that contains multiple chapters by different authors, bibliographies and reference sections can look rather cluttered:- oclc=704186906- oclc=704186906- oclc=704186906- oclc=704186906
As the list grows longer, the look becomes more cluttered with the unnecessarily repeated detail of full-length citations.  With harvc editors can link to shorter, less detailed contribution citations using standard implementations of sfn templates1957 and harv templates (like this: 1957 and also wrapped in ref tags). harvc may also be wrapped in ref tags so that it becomes part of the article's References section.1957

**Avoiding circular reference**
It may sometimes be necessary to cite a contribution of a source's editor or author such that last1 through last4 are the same as in1 through in4, an editor's preface for example. Such citations can, depending on placement, cause sfn or harv-family references to link directly to the citation instead of to the harvc template, or cause circular links (harvc linking to itself because its CITEREF anchor identifier is the same as the citation's CITEREF anchor identifier).  If id is set, harvc will use it as an anchor identifier; if id is not set, harvc will emit an error message when last1 through last4 are the same as in1 through in4.  
For example, to reference an editor's preface from article text, create a wikilink inside ref tags:

Write a harvc template with Stefferud preface 


**Example references section**

**Example bibliography section**
 oclc=704186906 - ignore-err=yes- ignore-err=yes- ignore-err=yes- ignore-err=yes- ignore-err=yes

**More than one contribution**
There are times when an author or authors will have contributed more than once to a work.  When this occurs, it is necessary to disambiguate the CITEREF links from the harv or sfn templates to the CITEREF id of the appropriate harvc template.
YYYYa → YYYYa → ...}
YYYYb → YYYYb ↑
In this example, author David Hunt contributed two appendices to Christmas Cacti: The Genus Schlumbergera and Its Hybrids.
There are two Harvard citation no brackets templates that are disambiguated:
 → 1995a
 → 1995b
These link to two harvc templates which use anchor-year for their CITEREF id and for the date in the harvc rendering as a visual aid for readers:
*:ignore-err=yes
*:ignore-err=yes
and the single citation template:
*:isbn=978-0-9517234-6-3

**Error messages**
emits these error messages:
harvc: author missing from source list.
:the source list parameters in1, in2, in3, and in4 form the template's CITEREF link to the full citation.  All are not required but must be used in order without numerical gaps.
harvc: invalid plain=yes.
:when used, anchor-year must be a three- or four-digit number and must have a lowercase CITEREF disambiguator. When the source does not have an identifiable year, use  or  with lowercase CITEREF disambiguator.
harvc: invalid plain=yes.
:the value assigned to display-authors must be a number greater than 0 or the keyword etal
harvc: invalid plain=yes.
:year is an integral part of the template's CITEREF anchor and link.  The value of year must be a three- or four-digit number with an optional lowercase CITEREF disambiguator. When the source does not have an identifiable year, use n.d. or nd.
harvc: missing plain=yes.
:year is missing; the parameter is required.
harvc: no authors in contributor list.
:this error message indicates that harvc can't find any of last, last1, author or author1 with an assigned value and so cannot make a usable CITEREF anchor.  Add at least one of the listed parameters.
harvc: required contribution is missing.
:this error message indicates that harvc can't find any of c, chapter, or contribution with an assigned value
harvc: required plain=yes parameter missing.
:this error message is emitted when the harvc template's CITEREF anchor identifier would conflict with the long-form citation's CITEREF anchor identifier.  See Examples
harvc: plain=yes / plain=yes mismatch.
:the year portion of  must match the year given in YYYY