SAS Studio

11月 122019
 

The t-test is a very useful test that compares one variable (perhaps blood pressure) between two groups. T-tests are called t-tests because the test results are all based on t-values. T-values are an example of what statisticians call test statistics. A test statistic is a standardized value that is calculated from sample data during a hypothesis test. It is used to determine whether there is a significant difference between the means of two groups. With all inferential statistics, we assume the dependent variable fits a normal distribution. When we assume a normal distribution exists, we can identify the probability of a particular outcome. The procedure that calculates the test statistic compares your data to what is expected under the null hypothesis. There are several SAS Studio tasks that include options to test this assumption. Let's use the t-test task as an example.

You start by selecting:

Tasks and Utilities □ Tasks □ Statistics □ t Tests

On the DATA tab, select the Cars data set in the SASHELP library. Next request a Two-sample test, with Horsepower as the Analysis variable and Cylinders as the Groups variable. Use a filter to include only 4- or 6-cylinder cars. It should look like this:

On the OPTIONS tab, check the box for Tests for normality as shown below.

All the tests for normality for both 4-cylinder and 6-cylinder cars reject the null hypothesis that the data values come from a population that is normally distributed. (See the figure below.)

Should you abandon the t-test results and run a nonparametric test analysis such as a Wilcoxon Rank Sum test that does not require normal distributions?

This is the point where many people make a mistake. You cannot simply look at the results of the tests for normality to decide if a parametric test is valid or not. Here is the reason: When you have large sample sizes (in this data set, there were 136 4-cylinder cars and 190 6-cylinder cars), the tests for normality have more power to reject the null hypothesis and often result in p-values less than .05. When you have small sample sizes, the tests for normality will not be significant unless there are drastic departures from normality. It is with small sample sizes where departures from normality are important.

The bottom line is that the tests for normality often lead you to make the wrong decision. You need to look at the distributions and decide if they are somewhat symmetrical. The central limit theory states that the sampling distribution of means will be normally distributed if the sample size is sufficiently large. "Sufficiently large" is a judgment call. If the distribution is symmetrical, you may perform a t-test with sample sizes as small as 10 or 20.

The figure below shows you the distribution of horsepower for 4- and 6-cylinder cars.

With the large sample sizes in this data set, you should feel comfortable in using a t-test. The results, shown below, are highly significant.

If you are in doubt of your decision to use a parametric test, feel free to check the box for a nonparametric test on the OPTIONS tab. Running a Wilcoxon Rank Sum test (a nonparametric alternative to a t-test), you also find a highly significant difference in horsepower between 4- and 6-cylinder cars. (See the figure below.)

You can read more about assumptions for parametric tests in my new book, A Gentle Introduction to Statistics Using SAS Studio.

For a sneak preview check out the free book excerpt. You can also learn more about SAS Press, check out the up-and-coming titles, and receive exclusive discounts. To do so, make sure to subscribe to the newsletter.

Testing the Assumption of Normality for Parametric Tests was published on SAS Users.

11月 062019
 

I have been programming SAS for a LONG time and have never seen much in the way of programming standards. For example, most SAS programmers indent DATA and PROC statements (I like three spaces). Most programmers do not like to see more than one statement on a line and most agree that there should be blank lines between program boundaries (DATA and PROC steps).

I thought I would share some of my thoughts on programming standards, with the hope that others will chime in with their ideas.

    • I like to indent all the statements in a DO group or DO loop. If there are nested groups, each one gets indented as well.
    • I prefer variable names in proper case.
    • I am not a fan of camel-case. For example, I prefer Weight_Kg to WeightKg. The reason that some programmers like camel-case is that SAS will automatically split a variable name at a capital letter in some headings.
    • I like my TITLE statements in open code, not inside a PROC. To me, that makes sense because TITLE statements are global.
    • There should be no conversion messages (character to numeric or numeric to character) in the SAS log. For example use Num = INPUT(Char_Num,12.); instead of Num = 1*Char_Num;. The latter statement forces an automatic character to numeric conversion and places a message in the log.
    • I always use the statement ODS NOPROCTITLE;. This eliminates the default SAS procedure name at the top of the output.
    • Although fewer and fewer people are reading raw text data, I like my @ signs to all line up in my INPUT statement.
    • I like to use the /* and */ comments to define all macro variables. For example:

Notice that I prefer named parameters in my macros, instead of positional parameters.

If this seems like too much work - SAS Studio has an automatic formatting tool that can help standardize your programs. For example, look at the code below:

Really ugly, right? Here is how you can use the automatic formatting tool in SAS Studio.

When you click this icon, the program now looks like this:

That’s pretty much the way I would write it. By the way, if you don't like how Studio formatted your code, enter a control-z to undo it.

For more tips on writing code and how to get started in SAS Studio – check out my book, Learning SAS by Example: A Programmer’s Guide, Second Edition. You can also download a free book excerpt. To also learn more about SAS Press, check out the up-and-coming titles, and receive exclusive discounts make sure to subscribe to the SAS Books newsletter.

Making your SAS code more readable was published on SAS Users.

1月 182019
 

It seems that everyone knows about GitHub -- the service that hosts many popular open source code projects. The underpinnings of GitHub are based on Git, which is itself an open-source implementation of a source management system. Git was originally built to help developers collaborate on Linux (yet another famous open source project) -- but now we all use it for all types of projects.

There are other free and for-pay services that use Git, like Bitbucket and GitLab. And there are countless products that embed Git for its versioning and collaboration features. In 2014, SAS developers added built-in Git support for SAS Enterprise Guide.

Since then, Git (and GitHub) have grown to play an even larger role in data science operations and DevOps in general. Automation is a key component for production work -- including check-in, check-out, commit, and rollback. In response, SAS has added Git integration to more SAS products, including:

  • the Base SAS programming language, via a collection of SAS functions.
  • SAS Data Integration Studio, via a new source control plugin
  • SAS Studio (experimental in v3.8)

You can use this Git integration with any service that supports Git (GitHub, GitLab, etc.), or with your own private Git servers and even just local Git repositories.

SAS functions for Git

Git infrastructure and functions were added to SAS 9.4 Maintenance 6. The new SAS functions all have the helpful prefix of "GITFN_" (signifying "Git fun!", I assume). Here's a partial list:

GITFN_CLONE  Clones a Git repository (for example, from GitHub) into a directory on the SAS server.
GITFN_COMMIT  Commits staged files to the local repository
GITFN_DIFF Returns the number of diffs between two commits in the local repository and creates a diff record object for the local repository.
GITFN_PUSH  Pushes the committed files in the local repository to the remote repository.
GITFN_NEW_BRANCH  Creates a Git branch

 

The function names make sense if you're familiar with Git lingo. If you're new to Git, you'll need to learn the terms that go with the commands: clone, repo, commit, stage, blame, and more. This handbook provided by GitHub is friendly and easy to read. (Or you can start with this xkcd comic.)

You can

data _null_;
 version = gitfn_version();
 put version=;             
 
 rc = gitfn_clone("https://github.com/sascommunities/sas-dummy-blog/",
   "c:\Projects\sas-dummy-blog");
 put rc=;
run;

In one line, this function fetches an entire collection of code files from your source control system. Here's a more concrete example that fetches the code to a work space, then runs a program from that repository. (This is safe for you to try -- here's the code that will be pulled/run. It even works from SAS University Edition.)

options dlcreatedir;
%let repoPath = %sysfunc(getoption(WORK))/sas-dummy-blog;
libname repo "&repoPath.";
libname repo clear;
 
/* Fetch latest code from GitHub */
data _null_;
 rc = gitfn_clone("https://github.com/sascommunities/sas-dummy-blog/",
   "&repoPath.");
 put rc=;
run;
 
/* run the code in this session */
%include "&repoPath./rng_example_thanos.sas";

You could use the other GITFN functions to stage and commit the output from your SAS jobs, including log files, data sets, ODS results -- whatever you need to keep and version.

Using Git in SAS Data Integration Studio

SAS Data Integration Studio has supported source control integration for many years, but only for CVS and Subversion (still in wide use, but they aren't media darlings like GitHub). By popular request, the latest version of SAS Data Integration Studio adds support for a Git plug-in.

Example of Git in SAS DI Studio

See the documentation for details:

Read more about setup and use in the available here as part of our "Custom Tasks Tuesday" series.

Using Git in SAS Enterprise Guide

This isn't new, but I'll include it for completeness. SAS Enterprise Guide supports built-in Git repository support for SAS programs that are stored in your project file. You can use this feature without having to set up any external Git servers or repositories. Also, SAS Enterprise Guide can recognize when you reference programs that are managed in an external Git repository. This integration enables features like program history, compare differences, commit, and more. Read more and see a demo of this in action here.

program history

If you use SAS Enterprise Guide to edit and run SAS programs that are managed in an external Git repository, here's an important tip. Change your project file properties to "Use paths relative to the project for programs and importable files." You'll find this checkbox in File->Project Properties.

With this enabled, you can store the project file (EGP) and any SAS programs together in Git, organized into subfolders if you want. As long as these are cloned into a similar structure on any system you use, the file paths will resolve automatically.

The post Using built-in Git operations in SAS appeared first on The SAS Dummy.

8月 292018
 

The concept of "current working directory" is important within any SAS program that reads or creates external files. In SAS, when you reference a file location with a relative path (for example, "./projects/mydata.pdf"), that file reference resolves to an absolute path by way of the working directory. You can control the initial working directory by modifying the shell scripts that launch the SAS process, or by specifying the simple SAS macro that allows you to learn the current working directory. The macro uses a trick to assign a SAS fileref to the current path ('.'), grab the full path of that fileref by using Read the article for the full source (it's only about 7 lines). Here's how you would use it:

56         %put Current path is %curdir;
Current path is C:\WINDOWS\system32

As you might infer from my example here, I'm running this on a managed Windows environment. Most users cannot write to the "C:\WINDOWS\system32" path (and would not want to), so any relative file paths in my SAS code would cause errors. Maybe you've seen something like this:

25         ods html file="./test.html";
NOTE: Writing HTML Body file: ./test.html
ERROR: Insufficient authorization to access C:\WINDOWS\system32\test.html.
ERROR: No body file. HTML output will not be created.

If I want to use a relative path, I need to change the current working directory. Fortunately, there's a simple way to do that.

Change the current directory in SAS

Use the

/* working path for my projects */
%let rc = %sysfunc(dlgcdir('u:/projects'));
 
ods html file="./test.html";
proc print data=sashelp.class; run;
ods html close;

I can use my account-specific environment variables to make these paths work for all users. For example, on Windows I can reference the USERPROFILE environment variable. (On Unix, I can use the HOME environment variable instead.)

/* working path for my projects */
%let user = %sysget(USERPROFILE);
%let rc = %sysfunc(dlgcdir("&user./Documents"));
 
/* create an output data folder if needed */
options dlcreatedir;
libname outdata "./data";
 
ods html file="./test.html";
data outdata.class;
 set sashelp.class;
run;
proc print data=outdata.class; run;
ods html close;

Here's my log output. Notice how the HTML file and the output data folder are both created at locations relative to my home directory.

25         /* working path for my projects */
26         %let user = %sysget(USERPROFILE);
27         %let rc = %sysfunc(dlgcdir("&user./Documents"));
NOTE: The current working directory is now "C:\Users\sascrh\Documents".
28         
29         options dlcreatedir;
30         libname outdata "./data";
NOTE: Library OUTDATA was created.
NOTE: Libref OUTDATA was successfully assigned as follows: 
      Engine:        V9 
      Physical Name: C:\Users\sascrh\Documents\data
31         
32         ods html file="./test.html";
NOTE: Writing HTML Body file: ./test.html
33         data outdata.class;
34          set sashelp.class;
35         run;

If using SAS Enterprise Guide, you can add DLGCDIR function steps to the startup statements that run when you connect to SAS, ensuring that your working directory starts in a valid location for SAS output. You can specify those statements in Tools->Options->SAS Programs, "Submit SAS code when server is connected." A SAS administrator can also add code to the AUTOEXEC file that runs when the SAS session begins, thus helping to manage this for larger groups of SAS users.

See also

The post Manage the current directory within your SAS program appeared first on The SAS Dummy.

6月 192018
 

When making a new piece of code, I like to use the smallest font I can read. This lets me fit more text on the screen at once. When presenting code to others, especially in a classroom setting, I like to make the font large enough to see from the back of the room. Here’s how I change font size in SAS in our three programming interfaces.

The post Changing font size in SAS appeared first on SAS Learning Post.

6月 092018
 

SAS Studio is the latest way you can access SAS. This newer interface allows users to reach SAS through a web browser, offering a number of unique ways that SAS can be optimized. At SAS Global Forum 2018, Lora Delwiche (SAS) and Susan J Slaughter (Avocet Solutions) gave the presentation, “SAS Studio: A New Way to Program in SAS.” This post reviews the paper, offering you insights of how to enhance your SAS Studio programming performance.

This new interface is a popular one, as it is included in Base SAS and used for SAS University Edition and SAS OnDemand for Academics. It can be considered a self-serving system, since you write programs in SAS Studio itself that are then processed through SAS and delivered results. Its ease of accessibility from a range of computers is putting it in high demand – which is why you should learn how to optimize its use.

How to operate

A SAS server processes your coding and returns the results to your browser, in order to make the programs run successfully. By operating in Programmer mode, you are given the capabilities to view Code, Log, and Results. On the right side of the screen you can write your code, and the toolbar allows you to access the many different tools that are offered.

SAS Studio

Libraries are used to access your SAS data sets, where you can also see the variables contained in each set. You can create your own libraries, and set the path for your folder through SAS Studio.

In order to view each data set, the navigation pane can also be used. Right click on the data set name and select “Open” to access files through this method. These datasets can be adjusted in a number of ways: columns can be shifted around by dragging the headings; column sizes can be adjusted; the top right corner has arrows to view more information; clicking on the column heading will sort that data.

 

In order to control your data easily, filters can be used. Filters are accessed by right-clicking the column heading and selecting the filter that best fits your needs.

How to successfully code

A unique feature to SAS Studio is its code editor that will automatically format your code. Clicking on the icon will properly format each statement and put it on its own line. Additionally, syntax help pops up as you type to give you possible suggestions in your syntax, a tool that can be turned on or off through the Preferences window.

One tool that’s particularly useful is the snippet tool, where you can copy and paste frequently used code.

Implementing and Results

After code is written, the Log tool can help you review your code, whereas Results will generate your code carried out after it has been processed. The Results tab will give you shareable items that can be saved or printed for analysis purposes.

Conclusion

These insights offer just a glimpse of all of the capabilities in programming through SAS Studio. Through easy browser access, your code can be shared and analyzed with a few clicks.

Additional Resources

Additional SAS Global Forum Proceedings
SAS Studio Videos
SAS Studio Courses
SAS Studio Programming Starter Guide
SAS Studio Blogs
SAS Studio Community

Other SAS Global Forum Programming Papers of Interest

Code Like It Matters: Writing Code That's Readable and Shareable
Paul Kaefer

Identifying Duplicate Variables in a SAS ® Data Set
Bruce Gilsen

Macros I Use Every Day (And You Can, Too!)
Joe DeShon

Merge with Caution: How to Avoid Common Problems when Combining SAS Datasets
Joshua M. Horstman

SAS Studio: A new way to program in SAS was published on SAS Users.

5月 012018
 

The title of this blog says what you really need to know: SAS Enterprise Guide does have a future, and it's a bright one. Ever since SAS Studio debuted in 2014, onlookers have speculated about its impact on the development of SAS Enterprise Guide.

I think that we have been consistent with our message that SAS Enterprise Guide serves an important purpose -- a power-user interface for SAS on the desktop -- and that the product will continue to get support and new features. But that doesn't stop folks from wondering whether it might meet sudden demise like a favorite Star Wars or Game of Thrones character.

I recently recorded a session with Amy Peters, the SAS product manager for SAS Enterprise Guide and SAS Studio. Amy loves to meet with SAS users and hear their successes, their concerns, and their ideas. Her enthusiasm for SAS Enterprise Guide comes through in this video, even as I bumble my way through the prototype of the Next Big Release.

Coming soon: the features of a modern IDE

In addition to a much-needed makeover and modern appearance, the new version of SAS Enterprise Guide (scheduled for sometime in 2019) addresses many of the key requests that we hear from SAS users. First, the new version blows open the window management capabilities. You can open and view many items -- programs, data, log, results -- at the same time, and arrange those views exactly as you want. You can spread your workspace over multiple displays. And you can tear away or dock each item to suit your working style.

Screenshot of Future EG

(in development) screenshot of SAS Enterprise Guide

Second, you can decide whether you want to work with a SAS Enterprise Guide project -- or just simply write and run code. Currently you must start with a project before you can create or open anything else. The new version allows you leverage a project to organize your work...or not, depending on your need at the moment.

And finally, you can expect more alignment and collaboration features between SAS Studio and SAS Enterprise Guide. We see that more users find themselves using both interfaces for related tasks, and presenting a common experience is important. SAS Studio runs in your browser while SAS Enterprise Guide works on your desktop. Each application has different capabilities related to that, but there's no reason that they need to be so different, right?

For more information about what the future will bring, check out the communities article that recaps the SAS Global Forum 2018 presentation. It includes an attached presentation slide deck with many exciting screenshots and roadmap details. All of this is subject to change, of course (including release dates!), but I think it's safe to say the future is bright for SAS users who love their tools.

The post A productive future for SAS Enterprise Guide appeared first on The SAS Dummy.

3月 222018
 

Generating HTML output might be something that you do daily. After all, HTML is now the default format for Display Manager SAS output, and it is one of the available formats for SAS® Enterprise Guide®. In addition, SAS® Studio generates HTML 5.0 output as a default. The many faces of HTML are also seen during everyday operations, which can include the following:

  • Creating reports for the corporate intranet.
  • Creating a responsive design so that content is displayed well on all devices (including mobile devices).
  • Emailing HTML within the body of an email message.
  • Embedding figures in a web page, making the page easier to send in an email.

These tasks show the need for and the true power and flexibility of HTML. This post shows you how to create HTML outputs for each of these tasks with the Output Delivery System (ODS). Some options to use include the HTML destination (which generates HTML 4.1 output by default) or the HTML5 destination (which generates HTML 5.0 output by default).

Reports

With the HTML destination and PROC REPORT, you can create a summary report that includes drill-down data along with trafficlighting.

   ods html path="c:\temp" file="summary.html";	
 
   proc report data=sashelp.prdsale;
      column Country  Actual Predict; 
      define Country / group;
      define actual / sum;
      define predict / sum;
      compute Country;
         drillvar=cats(country,".html");
         call define(_col_,"url",drillvar);
      endcomp;
   run;
 
   ods html close;
 
   /* Create Detail data */
 
   %macro detail(country);
   ods html path="c:\temp" file="&country..html";
 
   proc report data=sashelp.prdsale(where=(country="&country"));
      column Country region product Predict Actual; 
      compute actual;
         if actual.sum >  predict.sum then 
         call define(_col_,"style","style={background=green}");
   endcomp;
   run;
 
   ods html close;
   %mend;
 
   %detail(CANADA)
   %detail(GERMANY)
%detail(U.S.A.)

Generating HTML output

In This Example

  • The first ODS HTML statement uses a COMPUTE block to create drill-down data for each Country variable. The CALL DEFINE statement within the COMPUTE block uses the URL access method.
  • The second ODS HTML statement creates targets for each of the drill-down values in the summary table by using SAS macro language to subset the data. The filename is based on the value.
  • Trafficlighting is added to the drill-down data. The added color is set to occur within a row when the data value within the Actual Sales column is larger than the data value for the Predicted Sales column.

HTML on Mobile Devices

One approach to generating HTML files is to assume that users access data from mobile devices first. Therefore, each user who accesses a web page on a mobile device should have a good experience. However, the viewport (visible area) is smaller on a mobile device, which often creates a poor viewing experience. Using the VIEWPORT meta tag in the METATEXT= option tells the mobile browser how to size the content that is displayed. In the following output, the content width is set to be the same as the device width, and the  initial-scale property controls the zoom level when the page first loads.

<meta name="viewport" content="width=device-width, initial-scale=1">

 ods html path="C:\temp" file="mobile.html" 
 metatext='name="viewport" content="width=device-width, initial-
 scale=1"';
   proc print data=sashelp.prdsale;
      title "Viewing Output Using Mobile Device";
   run;
   ods html close;

In This Example

  • The HTML destination and the METATEXT= option set the width of the output to the width of the mobile device, and the zoom level for the initial load is set.

HTML within Email

Sending SMTP (HTML) email enables you to send HTML within the body of a message. The body can contain styled output as well as embedded images. To generate HTML within email, you must set the EMAILSYS= option to SMTP, and the EMAILHOST= option must be set to the email server. To generate the email, use a FILENAME statement with the EMAIL access method, along with an HTML destination. You can add an image by using the ATTACH= option along with the INLINED= option to add a content identifier, which is defined in a later TITLE statement. For content to appear properly in the email, the CONTENT_TYPE= option must be set to text/html.

The MSOFFICE2K destination is used here instead of the HTML destination because it holds the style better for non-browser-based applications, like Microsoft Office. The ODSTEXT procedure adds the text to the message body.

   filename mymail email to="chevell.parker@sas.com"
                       subject="Forecast Report"
                       attach=('C:\SAS.png' inlined="logo")
                       content_type="text/html";   
 
   ods msoffice2k file=mymail rs=none style=htmlblue options(pagebreak="no");
     title j=l '<img src="cid:logo" width="120" height="100" />';
     title2 "Report for Company XYZ";
 
 
   proc odstext;
      H3 "Confidential!";
   run;
 
   title;   
   proc print data=sashelp.prdsale;
   run;
 
   ods msoffice2k close;

In This Example

  • The FILENAME statement with the EMAIL access method is used.
  • The ATTACH= option specifies the image to include.
  • The INLINED= option specifies a content identifier.
  • The CONTENT_TYPE= option is text/html for HTML output.
  • The ODSTEXT procedure adds the text before the table.
  • The TITLE statement defines the “logo” content identifier.

Graphics within HTML

The ODS HTML5 destination has many benefits, such as the ability to embed graphics directly in an HTML file (and the default file format is SVG). The ability to embed the figure is helpful when you need to email the HTML file, because the file is self-contained. You can also add a table of contents inline to this file.

ods graphics / height=2.5in width=4in;
ods html5 path="c:\temp" file="html5output.html";
   proc means data=sashelp.prdsale;
   run;
 
   proc sgplot data=sashelp.prdsale;
      vbar product / response=actual;
   run;
 
   ods html5 close;

In This Example

  • The ODS HTML5 statement creates a table along with an embedded figure. The image is stored as an SVG file within the HTML file.

Conclusion

HTML is used in many ways when it comes to reporting. Various ODS destinations can accommodate the specific output that you need.

The many faces of HTML was published on SAS Users.

12月 192017
 

SAS' tag line is The Power to Know©, But what makes SAS so powerful? Ask our users and they'll tell you -- it's because SAS allows them to answer questions which previously could not be answered. How does SAS do this? SAS built a 4th generation programming language which makes [...]

What makes SAS so powerful was published on SAS Voices by David Pope

9月 162017
 

A while back, I wrote about the proliferation of interfaces for writing SAS programs.  I am reposting that blog here (with a few changes) because a lot of SAS users still don’t understand that they have a choice.

These days SAS programmers have more choices than ever before about how to run SAS.  They can use the old SAS windowing enviroment (often called Display Manager because, face it, SAS windowing environment is way too vague), or SAS Enterprise Guide, or the new kid on the block: SAS StudioAll of these are included with Base SAS.

DisplayManager9-4window

Display Manager / SAS Windowing Environment

EG7-12window

SAS Enterprise Guide

SASStudio3-5window

SAS Studio

I recently asked a SAS user, “Which interface do you use for SAS programming?”

She replied, “Interface?  I just install SAS and use it.”

“You’re using Display Manager,” I explained, but she had no idea what I was talking about.

Trust me.  This person is an extremely sophisticated SAS user who does a lot of leading-edge mathematical programming, but she didn’t realize that Display Manager is not SAS.  It is just an interface to SAS.

This is where old timers like me have an advantage.  If you can remember running SAS in batch, then you know that Display Manager, SAS Enterprise Guide, and SAS Studio are just interfaces to SAS–wonderful, manna from heaven–but still just interfaces.  They are optional.  It is possible to write SAS programs in an editor such as Word or Notepad++, and copy-and-paste into one of the interfaces or submit them in batch.  In fact, here is a great blog by Leonid Batkhan describing how to use your web browser as a SAS code editor.

Each of these interfaces has advantages and disadvantages.  I’m not going to list them all here, because this is a blog not an encyclopedia, but the tweet would be

“DM is the simplest, EG has projects, SS runs in browsers.”

I have heard rumors that SAS Institute is trying to develop an interface that combines the best features of all three.  So someday maybe one of these will displace the others, but at least for the near future, all three of these interfaces will continue to be used.

So what’s your SAS interface?