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Answer |
The RTL formula (syntax) checking process has been
improved in several ways to facilitate entry of RTL scan, signal, and
custom indicator formulas. The improvements are designed to facilitate
entry of technical indicator tokens in cases where multiple tokens are
needed for the same technical indicator. In addition, the improvements
enable the user to extend the technical indicator tokens available for
use in RTL formulas through the use of pre-defined technical indicator
"presets". RTL technical indicator tokens can reference other scans,
signal, and custom indicators directly by name.
Using Token Suffixes
Consider a scan to identify instruments whose 20 period simple
moving average has just crossed above the 100 period simple moving
average. To formulate this scan prior to these improvement you would
first add the MA token twice to the list on the right using the ==>
button. When you do this, Investor/RT will prompt for the setup for each
MA. You must then assure that each MA related token has a unique name so
you can refer to the different moving averages in the scan formula. You
might assign the token name MA_twenty to the first MA token and
MA_hundred to the second token. Then the scan formula can then be
entered:
MA_twenty.1 < MA_hundred.1 AND MA_twenty >
MA_hundred;
Notice the way the tokens are named in this example. First there is a
"real" token MA followed by an underscore and then some arbitrary
characters that make the token unique. This convention for naming tokens
is appealing because it makes clear that the token is in fact an MA and
the underscore provides a visual separator between the real token and
the suffix for improved readability, just as the period is used to
visually separate the entire token from the numeric qualifier .1. The
improvements made to the RTL formula setup are based on this technical
indicator naming convention. When technical indicator tokens are entered
directly into a formula without pre-defining them, Investor/RT will now
do much of the setup work for you. The new convention can be summarized
as follows:
When entering a technical indicator token, you can enter either:
- the actual token in upper case, e.g. MA, RAWK, CI
- the actual token in lower or mixed case, e.g. ma, rawk, ci
- the actual token in mixed case followed by a "suffix".
The suffix always begins with an underscore followed by a series of
letters, e.g. ma_st, ma_longterm, RAWK_one, RAWK_two
More succinctly, any technical indicator token can be entered in
mixed case optionally followed by a suffix that begins with an
underscore character. When you enter a formula using this convention
Investor/RT will do much or all of the token setup work. To see the
effect, open the RTL Setup Window (Setup: Scan or Setup: Signal). The
setup window will appear with the formula area blank and no tokens
listed on the right. Enter the following formula into the entry area:
ma_twenty.1 < ma_hundred.1 and ma_twenty >
ma_hundred
Press the "Check" button. Investor/RT will respond by adding
MA_twenty and MA_hundred automatically to the list on the right. Both of
these token names will be setup as MA tokens. Investor/RT will prompt
you with the MA preferences window so you can setup each token with the
appropriate moving average period. The MA setup dialog will show text
such as "Preferences for RTL Token MA_twenty" to indicate the name of
the token to which the setup pertains.
Using Indicator Presets as RTL Tokens
Suppose that you use 20 and 100 period moving averages often in scans,
signals, and custom indicators. If so, you may have setup MA presets for
20 and 100 period presets. Investor/RT uses the suffix naming convention
described above to identify references to technical indicator presets.
This enables any preset to be referenced directly in the RTL language.
The rule for referencing presets is as follows:
If an RTL technical indicator token has a suffix (e.g. _twenty) and
there is a preset defined for that indicator that has the same suffix,
then the preset indicator preferences will be automatically associated
with the RTL token without user prompting.
Suppose for example that you create presets for the moving average
indicator with names like "mySimpleMA_twenty" and "mySimpleMA_hundred".
To create presets, go to any setup window for an indicator, set the
preferences as you wish to record them, click on the Preset button and
choose "New". You will be prompted for a name for each preset. When
naming a preset that you may wish to use in RTL, put the suffix you want
to use at the end of the prefix name. In this case, we named our two MA
presets with suffixes _twenty and _hundred.
With the presets defined, the entry of technical indicator tokens can
proceed without pre-defining the tokens and without user prompting. Open
a new scan setup window and enter the formula:
ma_twenty.1 < ma_hundred.1 and ma_twenty >
ma_hundred
When you then press the "Check" (or "Scan" or "Save") button
Investor/RT will automatically create the two MA tokens giving them
names ma_twentry and ma_hundred. The setups for these two indicators
will be obtained from the MA presets found with the same suffixes. The
scan is fully specified with no user prompting windows. In essence, the
creation of indicator presets with suffixed names makes the suffix
visible to the RTL language. Note that the same suffix can be used in
names of various indicators. For example, you could have a MA preset and
an RSI preset both having names suffixed with "_twenty". Thus you can
write ma_twenty or rsi_twenty and Investor/RT will correctly obtain the
preset preferences without user prompting.
In the event no preset is found with the appropriate suffix, Investor/RT
will also check to see if it can find a preset having a full name that
exactly matches the suffix following after the underscore. For example,
if you make a preset named emaTen to refer to a MA token with a setup of
10 period exponential moving average, then the token MA_emaTen can be
used to refer to that MA preset. The full name of the preset follows the
underscore. Note that comparisons are case sensitive, thus MA_ematen
would not be recognized as a reference to the preset, while ma_emaTen
and MA_emaTen will work. The token before the underscore in not case
sensitive, but the suffix must match exactly.
How presets are named is up to each individual user. If you use short
preset names, like emaTen or stochRSI, you can refer to those presets
using RTL tokens using the full name. Longer names are more descriptive
but would be laborious to enter and hard to remember. With longer preset
name, an underscore suffix on the longer name gives you a shorter handle
for referring to the preset.
Referencing Scan, Signal, Custom Indicator Names
The indicator tokens SCAN and CI follow the same conventions described
above for technical indicator tokens. If you have a custom indicator
named "StochasticRSI" you can create a preset for this CI and name it "myStochasticRSI_srsi"
for example. Once this preset is defined, the token CI_srsi (or ci_srsi)
will be recognized in RTL formulas. When creating a new custom indicator
formula it is often useful to refer to other custom indicators or scans
(signals). Presets may not exist for each custom indicator, so
Investor/RT handles the CI and SCAN tokens further when no matching
preset is found. The rule is as follows:
A SCAN or CI token, when followed by a suffix, will be associated with
the scan or ci preset having that same suffix. If there is none, the
scan or ci token will be associated with the scan, signal, or custom
indicator whose full name matches the suffix. If there is none with that
name, the user will be prompted to name the associated scan, signal or
custom indicator.
Suppose for example you have two custom indicators with names:
StochasticRSI and SpecialAverage, a signal named "myBuySignal", and a CI
preset for StochasticRSI named myStochasticRSI_srsi. Here are a few RTL
tokens for making reference to these:
CI_myBuySignal (no prompt)
ci_myBuySignal (no prompt)
ci_mybuysignal (user will be prompted since the name match is case
sensitive)
ci_srsi (no prompt, reference StochasticRSI via the preset)
ci_StochasticRSI (no prompt, references StochasticRSI directly by
name)
scan_myBuySignal (no prompt)
When entering formulas, it may sometimes be useful to review a list
of all defined custom indicator names or signal/scan names as an aid to
entering the correct spelling of the name or suffix. This can be
accomplished by clicking the RTL button on the main toolbar. Choose Open
Custom Indicator from the ensuing popup menu to see a list of all custom
indicators. The list of names can be dismissed at any time without
actually opening anything by clicking the close box in the window title
bar.
Note that the special handling of RTL technical indicator tokens that
have an underscore suffix is a formula writing convention that speeds
entry and setup of RTL formulas. The RTL language itself has not
changed. You can still setup indicator tokens in advance of entering
your formula syntax and you can assign names to tokens with or without
an underscore suffix. All scans, signals, and custom indicators
correctly setup before these improvements will continue to function as
before. |