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This statement will retrieve a string designating the PDF/A conformance level of the importeddocument if it conforms to a PDF/A level, or none otherwise. The returned stringcan be used to set the PDF/A conformance level of the output document appropriately,using the pdfa option in PDF_begin_document( ).Copying the PDF/A output intent from an imported document. In addition to queryingthe PDF/A conformance level you can also copy the PDF/A output intent from animported document. Since PDF/A documents do not necessarily contain any output intent(unlike PDF/X which requires an output intent) you must first use pCOS to checkfor the existence of an output intent before attempting to copy it.Cookbook A full code sample can be found in the Cookbook topic pdf_flavors/import_pdfa.This can be used as an alternative to setting the output intent via PDF_load_iccprofile( ),and will copy the imported document’s output intent to the generated output document.Copying the output intent works for imported PDF/A and PDF/X documents.The output intent of the generated output document must be set exactly once, eitherby copying an imported document’s output intent, or by setting it explicitly usingPDF_load_iccprofile( ) with the usage option set to outputintent. The output intent shouldbe set immediately after PDF_begin_document( ).9.5.4 Color Strategies for creating PDF/AThe PDF/A requirements related to color handling may be confusing. The summary ofcolor strategies in Table 9.15 can be helpful for planning PDF/A applications. The easiestapproach which will work in many situations is to use the sRGB output intent profile,since it supports most common color spaces except CMYK. In addition, sRGB is known toPDFlib internally and thus doesn’t require any external profile data or configuration.Color spaces may come from the following sources:> Images loaded with PDF_load_image( )> Explicit color specifications using PDF_setcolor( )> Color specifications through option lists, e.g. in Textflows> Interactive elements may specify border colorsTable 9.15 PDF/A color strategiesoutput intentCIELab 1color spaces which can be used in the documentICCBased Grayscale 2RGB 2 CMYK 2none yes yes – – –Grayscale ICC profile yes yes yes – –RGB ICC profile, e.g. sRGB yes yes yes yes –CMYK ICC profile yes yes yes – yes1. LZW-compressed TIFF images with CIELab color will be converted to RGB.2. Device color space without any ICC profileIn order to create black text output without the need for any output intent profile theCIELab color space can be used. The Lab color value (0, 0, 0) specifies pure black in a device-independentmanner, and is PDF/A-conforming without any output intent profile(unlike DeviceGray, which requires an output intent profile). PDFlib will automatically212 Chapter 9: Generating various PDF Flavors